Skip to main content

Full text of "Report on the ENIAC (Electronic numerical integrator and computer)"

See other formats


Report on 

THE ENIAC 

{Electronic Numerical Integrator and Computer) 



Developed under the supervision of the 
Ordnance Department, United States Army 



MAINTENANCE MANUAL 



UNIVERSITY OF PENNSYLVANIA 
Moore School of Electrical Engineering 

PHILADELPHIA, PENNSYLVANIA 

June 1, 1946 



A REPORT ON THE EHIAG 
(Electronic Numerical Integrator and Gomputor) 



Report of Work under Contract No. "/_670-0RD-4926 



Be cvreen 



Oi-d nanca De-DartrAont .^ United Sta tes Army 
'■Yashiiy^t on. D. Cj_ 

and 



_The Univorsity of Pennsylvania 

MP-°J'ff..S£fr_ool^. of j^.^P! ^"'^^^ Q^^ E ngin eering: 
ph iladolph ia. Pa. 



This is copy No. 19 
of 25 bound copies of 
this report. 



I 



TK 



THE ]HAINTENMCE MANUAL 

by 

C. Chu H. D. Huskey 

J, A, Cummings T. K, Sharpless 

J. H. Davis R. P^ Shaw 



Moore School of Electrical Engineering 
University of Pennsylvania 



r 



PREFACE 
The Report on the ENIAC consists of five separately bound parts, 
as follows: 

1. ENIAC Operating Manual 

2. ENIAC Maintenance Manual 

3. Part I, Technical Description of the ENIAC 

Volume I (Chapters I to VI) 

4. Part I, Technical Description of the ENIAC 

Volume II (Chapters VII to XI) 

5. Part II, Technical Description of the ENIAC 

Included with the Operating Manual and Parts I and II of the Technical 
Description are all drawings (see table 0,3 below) which are required for 
understanding these reports. The Maintenance Manual assumes access to the 
complete file of ENIAC drawings. 

Part I of the Technical Description is intended for those who 
wish to have a general understanding of how the ENIAC works, without con- 
cerning themselves with the details of the circuits; it assumes no knowledge 
of electronics or circuit theory. Part II is intended for those who require 
a detailed understanding of the circuits. Its organization, to a great extent, 
duplicates that of Part I so as to make cross referencing between the two parts 
easy. 

The ENIAC Operating Manual contains a complete set of instructions 
for operating the ENIaC, It includes very little explanatory material, and 
hence assumes familiarity with Part I of the Technical Description of the 
ENIAC, The ENIAC Maintenance Manual includes description of the various test 
units and procedures for testing, as well as a list of common and probable 
sources of trouble. It assumes a complete understanding of the circuits of 
ENIAC, i.e. a knowledge of both Parts I and II of the Technical Description 
of the ENIAC. 



The Report on the EMIAC and thG complete file of ENIAC drawings 
constitute a complete description and set of instructions for operation and 
maintenance of the machine. The drawings carry a number of the form PX-n-m. 
The following tables give the classification according to this numbering system. 



Values of 
n 



1 
2 
3 
4 
5 
6 

7 
8 
9 
10 
11 
12 
13 



TABLE 0.1 
Division 



General 

Test Equipment 

Racks and Panels 

Trays, Cables, Adaptors, and Load Boxes 

Accumulators 

High Speed Multiplier 

Function Table 

Master PrograiTimer 

Cycling Unit and Initiating Unit 

Divider and Square Rooter 

Constant Transmitter 

Printer 

Power Supplies 



Values of 
m 



101-200 
201-300 
301-400 
401-300 



TABLE 0.2 



Subject 



Wiring Diagrams 

Mechanieal Drawings 

Report Drawings 

Illustration Problem Set-Ups, 






The reader of this report will be primaj'ily interested in the types 
of drawings listed in the following paragraphs, A table on page 4 gives the 
corresponding drawing number for each unit of the ENIAC. 

1) Front Panel Drawings. These drawings show in some detail the 
switches, sockets, etc., for each panel of each unit. They contain the 
essential instructions for setting up a problem on the MIaC, 

2) Front View Drawings, There is one of these drawings for each 
kind of panel used in the various units of the ENI/iC. These show the relative 
position of the trays and the location of the various neon lights. Since these 
drawings show the neon lights, they can be used to check the proper operation of 
the various units, 

3) Block Diagrams. These drawings illustrate the logical essentials 
of the internal circuits of each unit. That is, resistors, condensers, and 
some other electrical details are not shown; but com.plete channels (paths of 
pulses or, gates representing numbers or program signals) are shown in all their 
multiplicity. These drawings will be of interest to those v*io are interested 

in Parts I and II of the Technical Report, 

4) Cross-section Diagrams. These drawings are electronically complete 
except that only one channel is shown where there is more than one. Thus, these 
drawings show every resistor and condenser and any other electronic elements ■. 
belonging to any circuit. These drawings will be of particular interest to 

the maintenance personnel and to those reading Part II of the technical report, 

5) Detail Drawings. All other drawings of the ENIAC come under 
this heading, A complete file of drawings is available at the location of the 

ENInC. 



Table 0.3 
ENIAC DRn,.'/INGS 



Unit 

Initiating 
Unit 



Front Panel 

PX-9-302 
9-302R 



Fr'ont View 



PX-9-305 



Block Diagram 

■-i^i ll II n il I ' l 

px-9-307 



Cross - Section 



Cycling Unit 



PX-9-303 
9-303R 



PX-9-304 



PX-9-307 



iiccuniulator 



PX-5-301 



PX-5-305 



PX-5-304 



PX-5-115 



Multiplier 



PX- 



6-302 

6-302R 

6-303 

6-303R 

6-304 

6-30/4R 



PX-6-309 



PX-6-3O8 



Function Table 



Divider and 
Square Rooter 



PX- 



PX- 



7-302 
7-302R 
7-303 
7-303R 

10-301 
IO-3OIR 



PX-7-3'35 



PX-7-304 



PX-lO-302 



PX-lO-304 



PX-6-112A 
6-112B 



PX-7-117 
7-118 



PX-11-116 
11-309 
(C.T. and R.) 



Constant Trans- 
mitter 



PX- 



11-302 

11-302R 

11-303 

II-3O3R 

11-304 

II-304R 



PX-ll-306 



PX-ll-307 



Printer 



PX- 



12-301 

I2-3OIR 

12-302 

12-302R 

12-303 

I2-303R 



PX-12-306 



PX-12-307 



M&ster Pro- 
grammer 



PX- 



8-301 
8-3OIR 
8-302 
8-.302R 



PX-8-303 



PX-8-304 



Other drawings of particular interest: 



PX-12-115 



PX-8-102 



Floor Plan 
A.C, V/iring 
IHvI Reader and 
plugboard 



PX-l-302 
PX-l-303 
PX-11-119 
PX-ll-30 5 



lEM Punch and PX-12-112 

Plugboard PX-12-305 

Pulse ..innlifier and PX-4-302 

Block Diagrar-'i PX-4-301 



Interconnection of Multiplier end .^ccuimilators PX-6-311 
Interconnection of Divider and accuinulators PX-10-i307 



The front view drawings and the large front panel drawings (whose 
numbers do not end with "R") are bound as a part of the Operator's Manual. 

Included with the report is a folder containing .all the drawings 
listed in the above table except the large front panel (see above), A com- 
plete file of drawings is available at the location of the MIAC, 



I - 1 



I. INTRODUCTION TO MINTENANCE IViAITUAL 

1.1 Structure of Maintenance Manual 

The maintenance manual devotes a chapter to each unit of the 
ENIAC including one chapter to the a-c supply circuits. These various' 
chapters were written by the people who designed or helped to design the 
respective unit. 

Each chapter contains a list of the wiring diagrains and test 
charts referring to the circuits of that particular unit. It contains a 
section giving a testing procedure for the particular unit. Note that test 
procedures for each unit are also given in the oporating manual. In each 
chapter there is also a list of possible failures and their remedies. As 
time goes on the conscientious maintenance man will do well to keep a log 
book listing for each unit failtures enqountored, their symptoms, and the 
remedy. 

1.2 Notes and Warnings to Maintenance Personnel 

1) Keep in touch with operating group for any trouble which may 
develop. Notu repairs and troubles in log book. Keep log of 
all tube failures _ list each tube. 

2) This machine contains a number of dangorously hig^h voltages . 
Avoid working on any part while DC is on. 

Do not loavo off any covers. Remember the shells of tho 
metal tubes are at high potential with respect to the frame. 






to. 



b 



1-2 

3) Nover oporate machine with any DC fuses out except for special 
tests. Ylhen replacing a DC fuse bo sure they aro put in 
correctly - i.e. washer in cupfaco out, 

4) Make periodic chock on ventilating fans, 

5) Do not pound on plugs or plug- in units to got thorn in; use 
steady pressure. Avoid pulling on wires or cahlos to remove 
plugs; use case for grip, 

6) Koop covers on relays as much as possible; replace in same 
position to avoid spilling onto relay contacts dust which may 
have collected, 

7) Return all plug-in units and cables to proper racks when not 
in use, 

8) DONT'S 

(a) DON'T leave doors or covcrplatos leaning against relays 
or tubes or front panels, 

(b) DON'T hang probes on wires in traye. 

(c) DON'T mark panels with chalk or stick paper labels 
on them, 

(d) DON'T drop solder, nuts, lock washers, etc., inside 
machine and leavo them there. GET TxIEM OUT', 

1.3 General Remarks on Testing 
1.3.1 Standard Tost Problems 

Standard tost probloras chock for continuity of the programming 
sot-up unless there aro attached subsequences which operate simultaneously. 
Generally a standard tost problem cannot bo designed so as to test the 
numerical circuits completely. Hovrev&r, it comes much closer to completely 



I 



1-3 

checking the program control and conui^on progrcanming circuits. 
1.3.8 Systematic Unit Tosts 

Systematic tosts such cs those described in the operating manual 
are designed to check the nuraorical circuits and common programming circuits. 
If repeated with different program controls, they chock the program control 
circuits. The chapters of this manual give some other testing methods for 
certain of the units, 

1 . 4 Responsibility of Maintenance Personnel 

1) To have studied the four manuals (Operating Manual, Technical 
Reports I and II, and the Maintenance Manual) sufficiently to 
thoroughly understand the operation of each unit and the 
operating of the EKIaC as a whole. 

2) Knowing that a particular unit is failing to be able to find 
and remedy that failure. 

3) Knowing of the existence of a failure in the ENIAC to be able 
to assist the operating personnel in localizing the failure 

to particular units. However, the duty of isolating numerical 
and programming failures to a particular unit belongs primarily 
to the operating personnoj, 

1 . 5 ENIAC Drawings 

Tho maintenance personnel should have access to a file of drawings 
at the location of the ElJlAC. As part of the file of drawings there is a 
complete catalog of all tho drav/in-s of tho ENIaC. Only a few of the draw- 
ings arc referred to in tho various reports and in case of difficulty v^ith 
particular circuits tho maintenance man should refer to the catalog for 



I 



I 



1-4 

any other drawings which may bo of help, 

Drav/ings v/hich -rill be of particular help for maintenanc ing will 
be the various block diagrams and the cross-section diagrams of each unit, 

•"• • ^ General R emarks on Trouble Shootin g 

After a test problem has 'indicated a failure it becomes a problem 
of localization. 

1.6.1 Find the Unit that Failed 

To the operating personnel the type of failure found in the test 
problem may indicate the unit (or kind of unit) in v/hich the failure occurred. 
Various unit tests (such as thoso described in the operating manual) may be 
performed to assist in this localization process, 

1.6.2 Finding the Circuit that Failed 

The various unit tests are designed to localize tho failure to a 
particular circuit. Complete knowledge of part II of the technical report 
and efficient use of block diagrams will help in this procoss, 

1.5.3 Circuit Failures 

Tho most frequent failure in circuits is burned out tubes. 
Replace tubes in suspected circuits and test the tubes removed (seo Section 

on use of tho tube tester). Note that cathode failures in metal 
case tubes can bo detected at femoval time by comparing caso temperature 
Y/-ith that of other tubes. 

If all tho tubes in the suspected circuits test all right a static 
tost of tho circuits is indicated to chock against failures in wiring, 
resistors , or condensers. To assist in static and dynaiiuc testing tost 
charts have been prepared and certain tost equipment built (soo 
Tho charts have detailed instructions giving sv/itch settings, voltages. 



1-5 

pulso riso, duration, and fall tinios, pulso eonplitudos, ot cctora. 

The follovring principles in trouble shooting aro vrorth noting. 

1) If a circuit oporatos v/hon it shouldn't look for failure 
of an inverter tube. 

2) If <x circuit does not operate when it should look for failure 
of a gate or a buffer, 

•'■ • ''' Transient Foiluro s 

Transient failures can usually bo found by repeated programming 
of the suspoctod unit. As explained belov/ certain tost equipment has been 
built to assist in finding transient failures. 

Practically all circuits in the ENIAC were designed with at 
least a 2 to 1 safety factor. Thus, parameters (such as loads, voltages, 
ot cetera) can be varied considerably without effecting the operation of 
a normal unit. 

Thus, to assist in finding transient failures certain test oquip- 
ffiont (najncly, a variable oscillator and variable power supply equipment) 
has boen built. The variable oscillator oan be plugged into the cycling 
unit and the EIIIAC operated at frequencies above or below tlic standard 
frequency of 100 Ic.?, Th'^ variable power supply can be used to vary the 
voltages in a unit and thus increase the probability of failure. 



II - 1 

II. INITIATINa UNIT 
2.1 Circuits of the Initiating Unit 

I ■' " ■■■■■—^■■#1 ^ I II ■ I I I II I I III 11 f A I ■■ I pi ■■■!■ 

Tables 2,0 and 2.1 give a list of drawings pertaining to the 
Initiating Unit. The Interconnection dia(_;ram, PX-1-301 , shov/s the location 
of the plug-in units and gives the numbers of the chassis drawings. 





Table 2.0 
INITIATING UNIT PLUG-IN Ul'ITS 




No. of units 
used in Initia- 
ting Unit 


Plug- in Unit 


V/iring Diagram 


Static and 
D3m.amic Test 
Chart 


19 


Cycling' 'Unit 
Transmitters 


PX-9-102A 


PX-9-123 


6 


Transceivers 


PX-5-147 


PX-5-129 


i ' 

! 

1 

1 


Initiating 
Pulse Units 


Pr-9-105 


PX.9-125 


Reader- Printer 
Starting Unit 

Reader Interlocking 
Unit 


PX-9-104 
PX-9-103 


PX-9_122 

PX~9-124 


1 

1 


Reader Transmitter 
Unit 


PX-9-106 


PX-9-121 



II - 2 



Table 2.1 
OTHER INITIATING UIJIT CIRCUITS 



■zz^ 



Name 



Wiring 



Static Test Chart 



Oscilloscope 
DC Voltmeter 



Initial Clear Relay 



AC Voltmeter 



Start, Stop, and 
Door Sv/itch Shunt 



PX-9-115 



PX.9-126 



PX.9-118, 119 A, 
119B 



PX-9-115, 119 



PX.9-118A, 119 



PX-9-119 

(see Block Diagrajxi 

PX-9~307) 



2,2 Testing Program 

Tests for each of the plug-in units arc described on the test 
charts listed and covered in the section on the use of the Tost Bench. 

Tests on the pluj^-in units in place in the unit are outlined 



below. 



A) Cycling Unit Transmitters 

V/ith cycling unit on continuous operation observe CPP, 9P, 
I'P, RP on Oscilloscope on cycling unit. Presence of pulses of 
at least one inoh oinplitudo and e-qual width for each pulse indi- 
onjer^ all is well. If not replace one or more of the associated 
cycling unit transmitters. If no pulse at all, check on gates 
"Which produce the missing pulses for presence of pulse at output. 
Block diagram PX-9-307 will bo most useful here. 



II - 3 

B) Selectivo Clear Transceivers 

Connect each to a program line carrying continuous program 
pulses, then observe neon lights. If any unit fails, replace it. 

C) Initiating Pulse Units 

One of these units is used to produce a pulse synchronized 

with the Eniac when the initiating pulso switch is pushed. The 

other produces a synchronized pulse when the printer finishes 

an operation. To chock the first, connect output to input of 

one selective clear transceiver, set cycling unit on 1 add 

operation. Push initiating pulso sv/itch, upper neon should 

should 
light; pulsh 1 pulso 1 add switch, lower noon,^light, push 1 

pulse 1 add switch again, both neons out and transceiver neon 
should light. 

To test the other, corinect printer into a program chain. 
This will also test printer section of Reader-Printer Starting 
Unit. 

D) To test Reader-Printer Starting Unit, Reader Interlocking 
Unit, Reader Transmitter Unit, plug reader output into selective 
clear transceiver to check presence of output pulse. Set 
Cycling Unit on 1 add time. Push reader start switch, reader 
start neon on, reader interlock noon on, IBM reader should food 
card, reader finish neon on. After card food push 1 add button, 
roador start noon out, reader sjznchronizing noon on. After next 
1 add push reader interlock neon out, reader synchronizing neon 
out, transceiver neon on. 



I 



II - 4 

E) The Oscilloscope section needs no special mention as to 
service. The standard tests for the RCA 155A* scope arc appli- 
cable with the exception that the sweep frequency operates at 
approximately 60 CFS. 

P) Servicing of the two voltmeter circuits is straightf orv^ard - 
chocks for open circuits, short circuits, rosin joints, loose 
connection, etc, 

G) The initial clear relay circuits are shovm on PX-9-307, The 
time constant of ths condonser rsl&y circuit is sufficient that 
the relay should stay closed for not less than 1/2 second. In 
case of trouble look for failure of condenser or rolay. 



I 



tt, 
K 

w 

O 



0, 

V 

\ 



PM L EAJj U 'JAT-T" C ^£0 



To Pr\n-t£r 




Pn tNTER 






HP ULCn l^e s PX-8 

JULJUIJUlJUU 



70/ 



nn 

P.Soc 



K£7- 



lis 



■ni 






€1 P.>(-&i,i, 



O 'o. 

u; it' 



|t| |i| 



'■/^ x)r Kl'T ' 'ri.ni 



. 1- 



\-S-IIS ^ 

hi 



' I' I [5 

U^ JUUUUUUU 



n^nrinrinnrii 



M. p. Gate: Chassis 

PA -8 103 
M.P. pRONT Panel 

PX-S' ua 



PK />« PS 



^c^ 






^ nnnnnnf" 






a^ \'-n 






:'^ 



IS 






,5G 



^ 



^-J 







ThaiNS FQRr-iE:R Unit 



P.P. G^r£- C^^:52/:5 
PA- 8-/6^ CP'AnEL I) 

ft p. ^H/' / rcHi^G Pancl 
PX- 6- /0 9 
M. P. pRc ."} T Panel 
PX-8- /OS 



fiK Ptf PS 



OC 



cm 

SM SP 



r\^P5oc/<erP4ysi PX 



nn 



T/^HNsroR'^cR Unit 
P\- 8- 1 17 



;bf PX -3-/33 esB 



^■^ Jac v/i r 






rinni. 



^ 



?v 



il//./; 



r-8-i 



T.^f-MyLpX-&-/0 



uuuuuu 



} 



UULI 



'J 



O LAi N H 



nnnnnnnnnnri 



CYCLifJG Ukiit Gate 
PX-3-/3P- 



P5 PT Pl^ S(k 

izzi czi n [— I 

-^DC-^ At 



C.O.G^rECufissisa 
/^X -3-/35 



C. L/.S^iTC-ii \c 



■ifJSL 



/~X-3- i/Z 

C. U. Front Panb-l 
PX- 9 - / /4 



C.a.THf. v.. '-1 PX-3- lo;i 
Ui_UUUUUL_UUU 



pp 



CD 



C.LUcy 



1 r ^ ; — 1 1 — |r 1 r 
' I ii II 



s^r<^A'f. -J Py 3-/36 






^ ^ 



LiLlLJUIJUU 



T/^^iMS Foffnep Uf\iiT 

px-s-/'y 



nnnnnrr^nnn 

i I ' i I ' I 



r' II 



C.U. 7^-.A■,7>^ .'^'/-,3-/C^ 

ULUUUUUULUU I 



P/(-3-/IS' - 
I. U. Gate Chss-hs 
PX- 9- ,/g 

I. U. ^yvirc^ Pa'sIEil. 

PX-3- 1 13 
I. U. pfioNT Panel 



A.C POUJE K 



p- fpiri PuLS£spXF^\EK!L 



^ I 

il 



D. C. 



(*E^ T^ 









d £ 



L 



o 



tv- r~ 



0- >; 



—lUiL 



\^9k 






>•> v;,' 









Sl^^L^. 



T RANSrop MER Jrv / T 

PA- 9- 1/3 







t 



TPPCO:Vrv'PCT/0N DlAGP^N Op P1^6 PPP Pp C P fi M .'V P P , LYCL/r^G U N IT, ( I N IT / ^T / NG D £ [/ /CPS 









^5 



o 



I 

I 



^-1-k 















^ 






I 



5 






^ 5; 



1: O 



K^C^ 



k 






■^ U~|- -o 



ro 



^ 



5 
o 



^ 



^■_ 



•0 

'J 





Q 



Q 

I' 
a- 

<3 



MOORC SCHOOL OF ELECTRICAL ENGINEERING 

UNIVERSITY OF PENNSYLVANIA 



MP.,CU t lU. //VlSA'COZ/A/zCr/OA/ ^//?0-/^^A/ 



MATERIAL 



Drawn by : 

c J n-c 

Jan. /, /9^S 



FIN'SH 



CnttCK«K) Dy ; 



// 



'•^. c<. 



vs 






('" 



'^S 



'"PXP301 



Ill - 1 

III. CYCLING UNIT 

3,1 Circuits of Cycling Unit 

The cycling unit panel includes ton transmitter plug-in units of 
the master progreunmer (sco Chapter X) as well as the circuits of the 
cycling unit proper. The following tables and PX-1-.301 give the pertinent 
drawings tmd show tho position of the plug- in units. 



■^-«BI«CUU3 --^i.-^l T - 3 



Number of Units 



10 



6 



Nc<ine 



Table 3.1 
PLUG- IN UNITS 

VY 



Has tor PrograMHier 
Transmitters 



Cycling Unit 
Transmitters 



Cycling Unit Carry 
Gate Transmitter 



Cycling Unit Off- 
beat Unit 



Cycling Unit 
Oscillator 



On-beat Unit 



iring Diagram 



PX-8-105 



PX-9-10SA 



PX.9-102B 



PX,9-130 



PX-9-131 



PX-9-132 



Static and 
Dynamic Test 
Charts 



PX-8-122 



P3t.9-123 



P2U9-123 



PX-9-139 



PX.9-140 



PX-9-141 



I 



Ill - 2 



Name 

Top chassis 
Gat© A 



Table 3. 3 
CHASSIS CIRCUITS 



Gate B 



Position 
(tubes) 

1 aiid 2 

21 to 40 



!■ 



41 to 60 



¥ir ing 



PX-9_133 



PX-9_134 



PX.9-135 



Test Chart 



Static: 
PX-9-128 
PX-9_128A 

Dynamic: 
PX-9-129 



3. 2 Testing Procedure 

The routine testing of the cycling unit is best carried out in 
the following manner. With the operations switch on continuous and the 
oscillator switch on Liternal, tho various pulses and the carry gate are 
examined on tho viewing scope. Their presence is not sufficient for 
satisfactory operation but the pulses must all be of approximately the 
same shape and all signals at loast one inch high. Next, tho external 
oscillator should bo plugged in and the switch s<^ to External, the tens 
pulses should be examined on the viev/ing scope. Tho frequency should bo 
increased until either a shift of 1 pulse to tho right is observed in 
the tens pulses or one or more noon bulbe in cycling unit riyxg glow. 
The frequency at which this occurs should bo at least 160 kc. At this 
top speed the other pulses and gate should be again examined. The most 
common difficulty in the cycling unit is failure of the ring to count 
at these high frequencies. This can usually bo traced to trouble in the 
ring pulse standardizor. 

The 1 addition time mode of operation as v/oll as the one pulso 

tirao modo must also bo tested. Test tho 1 add mode at 100 Ice; and also 

at the top 



Ill - 3 

froquonoy. Presence of the tens pulses must also be chookod. This is dono 
by progr^'^ing Q- chain of tv/c programs, one ovcnt of which is to toll an 
accumulator to transmit. Then, continued pushing of the 1 pulse 1 add 
switch should result in the progrciiii chain stopping along and on the ono 
program, tho acoujnulator cycling, as ovidoncod by tho noons flashing, but 
tho same number roraaining in the accumulator. The same test should be made 
under 1 pulse time operation requiring, of course, 40 pushes of the switch 
to go through tho tv/o program scquonco. Should any of tho above tests fail the 
1 add gate, ring stop gate, 10 pulse flip-flop, and 10 pulse gate should 
be investigated first. 

Trouble in tho Viewing Scope may result from disturbed DC voltages 
which are produced in tho top pcuiel or due to failure of the svroep circuit 
which is located on Gate Chassis B, PX..9-135. This circuit is similar to 
one used in the A-R Scotio . type 256B, but uses different tubes. A discus- 
sion of this type of circuit vdll bo found in tho A-R Scope Manual . 



IV - 1 

IV. ACCUi'AULATOR 

4,1 Accumulator Cirauits 

Tho following tables and PX-5-302 give the numbers of drawings 
and tho location of various accumulator circuits. 





Table 4.1 

ACCmiULyvTOR PLUG- IN UNITS 


Number of Units 


Plug- in Unit 

1 


v/iring Diat;ram 


Static and 
Dynamic Tost 
' Chart 


10 


Dec ado 


FJU5-133 ' 


PX-5-126 


1 

2 


PM- Clear 
Rocoivor 


PX-5-108 ) 

i 

PX-5-14a ' 


PX-5-127 
PX.5-128 


8 


Transceiver 


PX-.5-147 j PX-5-129 


1 


Ropcator 


PX-5-149 PX-5-120 



Name 



Tablo 4.2 

ACCUMLrTDR dramngs 



Gato Chassis 



Position 
(tubes) 

41 to 60 



V/ir ing 
PX-5-117 



Tost Chart 



Static: 

PX-5-123 
DynoBiic: 

PX-5-124 



IV - 2 

4. 2 Testing; Frocoduro 

4.2.1 Numorical Circuits 

(a) RecGiving failures. 

Using the accumulator test cards described in the operating 
manual (section 2.2) the constant transmitter can be used to transmit 
numbers into an accumulator. 

In case of failure in this sort of teet, there are two possible 
procedures : 

1 ) Shift to another input and repeat the tost. 

2) PrograJii a transmission at one pulse time speed. 

Either of those procedures \vill generally determine v/hcther 
the failure is in the decade unit or in the input gate circuits. If the 
failure is in the decade unit replace it (repairing of plug-in units is 
discussed in the section on the test bench, Chapter XII), 

Any systematic tost shf^suld involve receiving numbers on all 
t'ivo inputs. 

4.2.2 Transmission Failures 

With a nuiabor such as F 44444 44444 in the doubtful accumulator, 
it should be programmed to add its contents to another accumulator at a 
one pulse time rate. The receiving accumulator should be knowi to bo 
operating correctly, of course. 

Consecutively, or simultaneously by using a second accumulator 
to receive, the subtract transmission circuits can be checked, 

4 . 3 Common Frograi^ming Circuits 

Simultaneously failure in all ten channels (or eleven channels 
in some cases) persisting with various program controls indicates failure 



I 



IV - 3 

in common prograrraning circuits, 
4,4 Prog:ram Control Failure 

If only one fails replace it. If inoro than one transceiver fails 
look for trouble in coranon prograjimiing circuits perhaps checking other 
transceivers. Failure of more than one program control flip-flop to 
reset indicates possible failure in the repeater ring circuits. 



fill-Y-^ 



a: 

I 









w 










--BI^' 



a 



J:i- 






Bay -^-J-o" ^6^^ 7S> / -^/^ 






s 



3 

'2 



-^-2 



:^D 



V 



I 











I — ^^ 1 



^D? 



^•PS 



>vJ- 



B^z-y-r,/ if 9 /I / 7 79 y 



HZZZZZ'^D 

a 










MOORE SCHOOL OF ELECTRICAL ENCIUCERIWC 
UNIVERSITY OF PENNSYLVAMIA 



/^CCUMULfiTO/^ lAyT£J^COA/A/£Cr/OAJ D/AS^AM. 



MATERIAL 



/ 



f rfMiKH 



T 



scnce 



/ 



/ 



\jrmt»r\ Oy 




' 7-Z'4S 



AfHirov«*«l by 



90^ 



PX-S-302. 



I 



V - 1 

V. HIGH SPEED MULTIPLIER 

5 . 1 Mult ip lier Circuits 

The circuits of tho Multiplier aro located on throe panels. 
The intorconnoction diagram, ?2-6-301, shov/s the ppsitionof the various 
circuits and the following table gives the numbers of some of tho 
portincnt drawings. 



Number used 

24 

6 

2 



Tabic 5.1 

PLUG- HI UIJITS OP THE MULTIPLIER 
Name 
TraiiGccivcr 

Buffer Units i PX-6-107 

i 

RsCGivor j PX~5-148 



•^•at.«BCSW«r"i; 



i Wiring Diagram j 
i FX-5-147 ! 



Tost Charts 
FZ-5-129 
PX-6-130 
FX-5-128 



^•2 Te stin ,^ Procedure 

The multiplier lends itself niCely to a routine Siutomatibally 
programmed test. The details of this test are given in the EiJIAC Operating 
Maiiual. 

In case of failure in the above test, the program should be 
stepped through by one addition time stops and tho partial products appear- 
ing in tho product accumulators inspected. This procedure if done in 
conjujiction with tracing the numbers course through tho multiplier (by 
use of tho block diagram, PX-6-308) may locate the failure. If this fails 
to locate trouble, stop by addition times to tho region of failure, then by 
pulse times. 



V ~ 2 



Table 5.3 

CHASSIS DRa:/IHGS 


Name 


position 


Wiring ' 


Test Charts 


Panel 


Tubes 


Icr Selector 


1 


3-20 


FZ- 6-101 


Static: 

Panel 1 PX-6-12S 
Panel 2 PX.6-126 
Panel 3 PX-6-128 

Djmamic: 

Panel 1 PX-6- 123 
Panel 2 PX-6-127 
Panel 3 PX-6- 129 


R.H. Multiplier Tabic 


1 


21 - 40 


PX-6-102 


L.H. Multiplier Table 


1 


41 - 60 


PX- 6-103 


lor Top Chassis 


3 


1 and 2 


PX-6-105 


Gato 


2 


41 ~ 60 


p]C- 6-108 


Gate 


3 


41 - 60 


PX-6-1CS 


Icand L.K. Selector 


2 


21 - 40 


PX-6- 110 


Icand R.H. Selector 


2 


3-20 


PX-6-110 


jR and L Shifter 

\ 
1 


2 


3-20 

and 
21 - 40 


FX-6-111 






V - 3 

By chocking tho pulso groups arriving at the product accumulators 
(and comparing this with tho actual products of the digits of tho numbers 
boing multiplied) bad tubes may bo found, 
5,3 Possible Failuros 

1) Failure of gate tubes in multiplier aclootor would cause 
table to pass nine pulses, 

2) Failure of gato tubes in multiplicand selector or in shifter 
v/ould cause zero pulses to arrive at the corresponding place in the 
partial product, 

3) Failure of buffer or inverters in the channels may cause 
either of the above effects, 

4) Failure of table output gates would cause 1, 2, 2', or 4 
pulses to fail to reach the product accumulator, 

5) Failure of drivers on the output would cause a digit to be 
missing from each partial product, 

6) Failure of program control transceivers. 

7) Failure of coiumon programming circuits. 



Panel No. J 



No l\/ r R I N s 



/?. H.sSH/Fre/9 
PX-(c-/// 






L.H.Sh/FT£R 

PX-(>'//l 



□ 
DC 



SO' 



sat" 



Gate: UhiiT'^3 rx-6-/09 
5vji-rcH P/iNEL py-6-//S 
Front Panel PX-6-II^ 



DC DC AC SN* SW SF" 



nnnn 

HultSocke 



nnnnnnn 

tPaneIPJ(-(,-IICC 



i a: 



TRfiNsrof^i^ER Unit 
PX-^-//3 



I 

ul 

f5 



Panel No. 2. 



Panel No: 1 



( ( ( ( I 

aofflSnSpSS 



'^^oAcc.^lO 



sc; scjsc;so;5c:|.54 5<:>^»t'9*=» 



Mult. Top Chassis PJ(-6-/0S 

/Multiplicand 
R. H.Selejitor 
PX-i>-IIO 



SD' 



S(f 



Multiplicand 
L. H. 6£LEcrop 
PX'(>-IIO 



SO' 



a 



ss' s/^' 

Gat£ Unit^Z PX-6-lOa 

Switch Panel Pi(-6-//S 

Fi^aNT Panel. Py-6-llH- 



J 



pr Phf 

pa 
oc oc 



: -ic^ SN' SfT SF' 



, nnnnnn 

MvaoocKn Pan£l 



nnnn 

PH-lli>B 



I 



TR^M3FoBneR Unit 

PA -6 -//a 



sc,- 
5A- 



iJ,ilia£H 



A-B 

J 



y 



i 
1^ 



^ 



*■ Tohcc.*lO 
^ToAcc.**S 



SC^SCjSCi &fe5qiS£,5<g5C,S<-^ 



Top Chassis FYS-fOS 
PI ULT I FL lER 

PX-lo-IOI 



T"S£B, 



R.H. MoLTi- 
PLi cfiTioN Table 
PX-U-IOZ 

D 



PC 

LZl 

DC 



so 



LH. Mult. Table. FX-^-JOJ 
Switch Pa netl PX- 6-1 IS 
FifONT Pauel PX-6>~im- 



nnnnnnnnnn 

Muu.3ocH£T Panel PX-(>-II(>A 



PL PA fw: 

□ □n 

DC DC AC 






6M SF 



TpftNsroRnER Unit 
PX-6-//F 



Re^ar Interconnect /o/y Dii^gp^m Or Multiplier 



I 

UJ 

^2 



PanslI 



n 

Sv^iTCh Pahil 
PX-&-/I5 



Panel 2 



— ^T SRc SP. SP4-- 



PX-6-115 



PANed.3 



ID 

SPi-S^ 

5v\IITCH P. 

PX-6-115' 



Front Viev^ 



B 



o 

<o ii i~ 



u 
in 

^ |H 
^ .0 ? 

OtSo 



ioQ 

n 10 






A 



1^ 

cc 10 " 



MOORE SCHOOL OF ELECTRICAL ENGINCCRIMC 

UNIVERSITY Of PENNSYLVANIA 



I NTERCONNECTIOI^ DiAGRAM Or H IGH- SpeED M U LTIPLIER 



MATERIAL 



FINISH 



Drawn by ; 

Jan. 8j 19'f-S 



ChflCHeo by : 

/r/?oit.l^/clKfcl 

Auj.JZmE' 



Aoorov 



9CAUC 



i^ 



l^PX-6'301 



VI - 1 

VI. DIVIDER MD SQUARE ROOTER 

6,1 Divider and Square Rooter Circuits 

The following tables give the numbers of some of the pertinent 
drawings of the divider and square-rooter. PX-10-303 shows the positions 
of the ohasses and the plug- in units. 



• 


Table 6. la 


_., ■-.-— -....^ — ■-— ^»^ 




DIVIDER AND SQUARE ROOTER PLUG- IN UNITS 


1 

Test Charts 


Number of Units 


Name 


Wiring 


10 


Roooivers 


— .., ... — ^ — ^ — .^^ 

PX-5-148 


PX-5-128 


8 


Transceivers 


PX-5-147 


P7^5-129 


Z 


Buffers 


PX- 6-107 


PX-6-130 


1 


Repeater 


PX-5-149 


PX.5-130 


1 


Decade Ring 
(Master Programmer) 


PX^8-101 


PX.8-125 



Table 6.1b 

DIVIDER AND SQUARE ROOTER CIRCUITS 


Name 


Position 
3-20 

41 - 60 
1 and 2 


Wiring 


Test Charts 


Gate No. 1 
Gate No. 2 
Top 


PX^lO-106 
PX-10-105 
PX^10..112 


Static: 

PX-10-115A-D 

Dynamic: 

PX-10-116A-C 



6. 2 Checking the Operation 

Since the divider and square rooter worka in conjunction with a 
number of accumulators the first thing to do is to systematically check all 



VI - 2 

these accumulators (see Chapter IV), 

Drawings PX- 10-403 and PX-10-404 show the numbers occur ing at 
various places in the accumulators during sample division and square root 
problemB. These problems may be done at one addition rate after a failure 
is indicated. 

Since part of the control circuits go to accumulators via cabl©a 
and trays the operator should carefully check these when trouble is 
suspected. The presence of the proper adaptors, et cetera, should be 
verified. 

Note that the square root of zero is the simplest test problem 
that the unit can be caused to do. 

6.2.1 Program Control Failures 

If any transceiver remains "on" then it should be replaced. If 

more than one remains on, then tho common programming circuits should bo 

inspected. Check in particular to ses if the program ring cycles as it 

should. If the program ring cycles as it should, inspect the clearing 
circuits. 

6.2.2 Numerical Circuit Failures 

Check the quotient place ring and the various pulso gates includ- 
ing the i 1 or +_ 2 receivers, 

6.2.3 Common Programming Circuit Failures 

Using the block diagram and a samplo division or square root 
problem the operator should proceed at one addition time (and perhaps 
ropoat at one pulse time rate) rato and note the first circuits v/hich fail 
to operate (as indicated by the noon lights on the front panels), Roforonco 
should bo made to PX-10-302, 



c^^^^^ d3-/(2 /^c>/j.^sy^'Vc>:>zr'yjLAy ^sj.c^o^' p3ft/ne>^ p ^/3a//i/(2 



\ 









■ Aoe^ JUiy^: -^r7/7^- t^/i 'Zryoaf/^J}/^^^ 3/- 



ffl 






^^ 



5J 



■ \ 



D 



\ 



<^ 



eg 

L<v 

,— HI 



3C7f?3(7 









D^ 



>3 



v-^o 



1 









^ 






I. 



.5 

I 



I 



'^ 



^ 



^ 



'^ 






^ 



^ 






"o 



□^ 



D 



\Q 






if7Aijosfife^ai'j_ 



I 



v?A/3:>s//v^_l 



K 



:**<: 



^SA/-3VSff¥'i/J 






.^z 



atyA/37sw(/i/_l 



'ssrt/sosfvvd'j 



^ lH-S-)(<^ i''3A/3:imei^2 






i 

I 





















^^ 



~"i»i 



M 






MOORE SCHOOL OF ELECTRICAL ENGIHCERIiHC 
UNIVERSITY OF PENNSYLVANIA 



D/^. lA/T£ie(:oA/A/scr/^A/ D//^<y^ ^M 



MATERIAL 



PINJISM 



5C/»Ct 



/ 



Lcawn oy 




^'/29/¥S 






<*oorciv«o ov 



/ 



PX-/0-50Z 



T'ABJ.^ 6-2 
SI7ISI0N - ILLUSTJt;.TI7E PI10BLI<:M 
Problem: Divide P 2090070 000 by P 230 000 000. liound answer off to 4 places. Ho intHrlock, 



Period 



Add. 
Time 



II 



2 



Quotient AcGunulQtor 



Receives 



Stores after 
Heoeiving 



Bhif1 



ahifti- 



6 

L 



P 100 000 000 



l_ll 

12 



III 



13 
Ik 

15 
16 



J-7 



M 9 990 000 000 



I?umerator Hccuiaulator 



Receive 8 



Stores Hfter 
i^ceiving 



f 209 070 000 



P 100 000 000 



P 090 000 000 



P 001 000 000 



u 9 770 000 000 



H 9 790 700 000 



P 230 000 000 



P 209 070 000 



DonoDinator 
Accumulator 



Keceives durina 
period 1 and store* 
thereafter. 



P 230 000 000 



Shift Accumulator 



Receives 



u 9 979 070 000 



M 9 790 700 000 
V Oi^O 700 000 




P 091 000 000 



h- 



IV 



19 



20 
21 
22 

2K 



25 



P 000 000 000 



P 091 000 000 



P 207 000 000 
M 9 770 000 000 



U 9 770 000 000 



P 21)7 000 000 

u 9 977 000 000 






n 9 770 000 000 



P 230 000 000 
P 230 000 000 
P 230 000 000 
P 230 000 000 



P 000 000 000 
P 230 000 000 
P kbO 000 000 
P 690 000 000 



M 9 790 700 000 



Nyv\A/^/V 



i^toros after 
Receiving 



M 9 790 700 000 



P 230 000 000 j P 920 000 000 



^„._,u 



program output puis a and answer dispoeal signal is truiisnittad 



Answer Js transmitted fron quotient accuc.ulator. 



P 207 000 000 



N/W-^'W^' 



M 9 770 000 000 



N/>/V^/V^/' 



P 207 000 000 



M 9 770 000 000 







TABLE 6-3 

SQUARE HOOT - ILLUSTliATIVE PROBUDi 
iToblon: i-iad Np Ofil 360 ^0 . Hound answer off to U placos. No interlock 



.^ 



Period 




II 



shift 



Add. 
Tine 



2 
3 



Numerator (xiadicand) Aocumulator 



Hecoives 



p 0^1 360 ik)o 



5 

6 



4"; 



11 



rf- 



ahift 



10 



11 



12 



M 9 900 000 000 



M 9 ^13 604 000 



P 190 000 000 



P 036 040 000 
M 9 ^19 000 000 



III 



IV 



15 
1^ 

19_^ 

20 



21 
22 



23 



25 



stores after receiving 



p ofii 360 ik)0 



U 9 9«ll 360 1^00 



^A/A.'^y\/^/ 



M 9 &I3 6o4 000 
P 003 b04 000 



v^/Ny^s/ VN/V 



P 036 040 000 

M 9 ^55 o^k) 000 



M i 550 JK)0 000 I U ^ 550 1^00 000 
P 1^2 000 000 



P 1^2 000 000 

P 1^ 000 000 
P 1^ 000 000 
P 1^2 000 000 



"2^ 



M ^ 732 ^0 000 
M i 91^ '^O 000 
M 9 096 400 000 
U 9 27^ UOO 000 

M 9 46o ^0 000 



Dononinator (2 root) Accumulator 



Raceiyes 



iitores after aeceiving 



.>i1aV«9 1ir- ■ 



P 100 000 000 



P 2 00 OOP OOP 
H 9 900 000 000 

H 9 990 000 000 



M 9 9^0 000 000 
P 010-000 000 
P 0^001 000 000_ 

P 002 000 000 
M 9 999 000 000 



i,i 9 99^ 000 000 



P 100 000 000 



Z 3Q° 000 000 
p q 200 000 000 

P 190 000 000 



P 170 000 000 
P ISO 000 000 
PJO 1^1 JXJO 000 

P 1^3 DOO 000 
P 1^2 000 000 



P 1^0 000 000 



Program outputpulBe and answer disposal 3i£5nal_is_tjraj^ 



Answer is transmitted fnxi dononinator accuraulutor. 



Shift AocuEiulator 



Receives 



iitorea after reoeiving 



M 9 ^13 6on 000 



P 036 040 000 



N/N X 



M i ^50 400 000 



M 9 ^13 60H 000:„ 



P 036 0^ 000 



v-X^N/^ 



M ^ 550 !l00 000 



|l! 



VII - 1 

VII, FUNCTION TABLE 

7.1 Function Table Circuits 

The function tublo is locatod on two panels and there is the 
portable table ■■/^/hich plugs into both panols,. Tables 7,1 and 7,2 give some 
of tho pertinent drav/ing numbers and PX- 7-301 shows the location of the 
various circuits. 



Table 7,1 

PLUG- IK UNITS 



Number of Units 



11 



Name 



Transceivers 
Portable Table 



Wir ing 



I 



PX-5-147 

PX-7-134 

and 
PX-7-135 



Test Charts 



PX-5-129 



7.2 Operation Test 

A test sequence similar to that described in section 2,4 of the 
operating manual is set up. After initially cloarinr:, set cycling unit to 
1 add, and run tlirough 3 or 4 comploto cycles of the proi^ram, observing 
both the neons on upper panel of function tablo, and nujubers in accumulators. 
Push initiating button, thon 1 pulse-ludd button repeatedly; vfhen program 
ring is on second (-2) sta^^e, next push of button will cause argument to 
bo sent to function table; next push should cause u.iits ring to move 2 
stages further; second push after this should cause function to be transmitted 
to accumulators and function table rings to be cleared, 

Aftor this preliminary chock, return cycling unit to continuous 
operation, initially clear, and run through 100 argument values. At each 



stage of this process the aecumulators should indicate the argument and the 



VII - 2 



' 


Table 7.2 

FUNCTION TABIIE CIRCUITS 






Name 


Position 


Wiring 


Static 
Test Charts 


Dynaiaic 
Test Charts 


Panel 


Tuhos 


Top 


1 


1 and 2 


PX.7-119 


PX-7-137 

A and B 


PX-7-136 


Upper Function 
Selector 


1 


11 - 20 


PX.7-120 


Lower function 
Selector 


1 


21 - 40 


PXr.7-121 


Gate 


1 


41 - 60 


F3U7-122 


Top 


2 


1 and 2 


PX-7-126 


PX-7-139 


PX-7-140 


Gate A 


Z 


3-20 


PX-7-127 


Gate B 


Z 


21 - 40 


P3U7-128 


Gats C 


z 


41 - 60 


PX-7-129 


Gate D 


2 


61 - 80 


PX-7^130 



VII - 3 

corresponding function as set up on the portable table. To check -2 and -1 
arguments, set function table program sivitch to -2 and initially clear; then 
function shovm for argument is that sot on -2 row of switches and that 
shavn for 1 argument is that set on -1 row (Note that, since correction 
pulse goes into argument accumulator at beginning of cycle, zero argument 
Cannot be transmitted immediately after initially clearing; to get zero 
argument 4 either cycle around until argument accumulator shows 100, or pull 
out argument input cable at function table). To check 100 and 101 arguments, 
set program switch to +2 and cycle around until argument accumulator shov/s 
98 and 99 respectively. 

If in the preceding tests the progi'am switch is set to "subtract* 
instead of "add", leaving all subtract pulse switches at »0«, the function 
transmitted should be the nines complements of the numbers sot on the 
switches, 

7,3 Test Procedure 
7,3.1 Rings - frecjuenoy 

To check frequency toleranC(i of rirtfesi pull out tUbes specified 
and feed variable oscillator output to pin 8 of socket from \vhioh tube was 
removed in case of argument register; pin 3 in case of program ring; use a 
series condenser ; other side of oscillator output goes to ground. Connect 
oscilloscope to any convenient static output; these points are the ones to 
which are connected wires in the cable going to neon bulbs on front panel. 
Rings should count at frequencies up to 180 kc. 



VII - 4 



To test ring 


Pull out tubes 


Units 
Tens 

Program 


D42 

H42 


D49, E49, P49 j 



7.3.2 Rings Voltage Tolerance 

Use adaptor made for this purpose together with variable power 
supply; rings should be cycled continuously at 100 kc using variable 
frequency oscillator as in checking frequency tolerance. Rings should 
count at voltages from 120 to 300 volts. 

7.3.3 Oscilloscope Check of Function Table Outputs 

As additional check on operation, set up. continuous prograir.. No 

K n 

argument is ueod, Obsorvc output by plugging triple connector into output 
socket, with a tray load box plugged into one of the throe outputs; the 
scope probe can then bo inserted in one of the other outputs. With program 
sot to jxnd "add", the number of pulses observed on each channel should bo 
the same as the number sot on the corresponding switch. Operation of 
subtract pulso switches caJi be chocked by observing appearance of 1' pulso 
on an output channel when corresponding subtract pulse switch is sot to 
"S*. On PM channels, 9 pulses should appear if either table or master 
switch is set to "ij". PM positions on constant svvitches are most conve- 
niently checked by observing result of changing corresponding master PM 
switch from *P" to "M" or vice versa. 



7 , 4 Trouble Shooting Procedure 

In the following list will bo found a number of cases of abnormal 
operation together v;ith their probable causes and remedies. Before making 



VII - 5 

any other tests, seo that no switcjhes arc set half-way botwoon dotent 
positions, 

a. All rings operate continuously - may be defective transceiver; 
check to sec if any transceiver neons remain on. If only 

one remains on, replace defective unit. If more than one 
remain on, check clear gates (A48, B48 , C348) and clear tubes 
(A49, B49, C49); also initial clear buffer (D48). 

b. Program ring cycles continuously but argument ro/^istor 
remains cleared - chock repeater input gates (D4S, E49, P49). 

c. PrograiTi ring fails to cycle - chock as in b. above; also 
check pulse former tubes (049, H49, J49). Also check ring 
tubes, particularly if ring stalls on any except first stago, 

d. Argument is not roccivod but shifting takes place normally - 
check tubes K48, L48 ; if only one digit of argument is 
received, check D42, H42, 

e. Neither argument nor shift pulses received - chock pulso 
formers (B42, C4S, A41; also J42, K42, L42), Check ring tubes 
if this fails; if ring stops on any except first stage (zero 
position), it is almost certain that a ring tube is defective, 

f. Erroneous transmission or failure of transmission for ten 
adjacent argument values, others OK - check corresponding 
selector input £,ates (on top chassis of panel l), 

g. Erroneous transmission or failure of transmission for all 
arguments having a given units digit (for example, 8, 18, 
28, 38, etc.) - check vertical drivers (row 26 on panel 1), 



VII - 6 

h. Combination of f. and g. -. chock 807 Doloctor tube dt ixiter- 
seotion of defective row and column, 

i. No numbor transnuttod on a given digit channel - check tubes 

corresponding to that di-it Y/hich appear in block marked 

"table controlled digit output channsl" or "master switch and 

constant transmitter" on drawing PX-7-118. If PM channel 

is defective, chock corresponding tub^^s. 

j. Failure of a given figure to be transmitted on any channel - 

tubes on 
check corresponding panel 2 (see block marked "output gates 

and driver circuits" on drawing PX-7-118), 

k. Spurious transmission on a given digit channel - check 

corresponding output gate inverters and output gates. 






o) 



fv 









Q. 






I 



5 



^ 



319hi± NOlllNDJ JQ UJ{^yOVI(J NO I103N NODU^ IN f 



K 

W 

k: 






I 



I 






■s. 

^ si 












Q. 



I 



kj 

k 

k 






I 
N- 






-AVd± 3JVt)-3ST0fJ ohizinouhonA^ oj_ »- 







vj 

k 






f>4 



•I 

k 

k 



rv 

I 

k 






k 

k- 



k 



<n 

:j^ ^ rvj 

k 



V) 



■o 






^k 

*«J 
k 

k 

k 



k 

o 
k 

k 






~-v 

I 

k 



vl 

kj 

k 

I 

k 
k 
k 









5Dt 



<0 

k 



vl 



I 



k 



<\j 



Oi 



"UN 



■ A>/yi 3I^C)-3^lnj Vn//Z/NOi/iVVNA£ 01 »- 



V, 

to 






kj 

k 

vl 

kj 

5 



Q 

V 

lo 

*^ 

kj 
k 






■♦I 

I 1 
•Ml 



MOOif SCHOOL OF ELECTRICAL ENCINCCRINC 
UMIVEKSITY OF PENNSYLVAfllA 



ruNCTioN Table / nterconnect/on Di^gr/^m 



MATffllAk 






FIN»SH 









•CUT 



PX' 7-301 



' 



VIII ~ 1 

VIII. CONSTAT TRAl'ISiJITTER AND IBM READER 

Q • 1 Circuits of tho Constant Transmit ter 

The following tables give tho drawings pertinent to maintaining 
the constant transmitter. PX-11-301 shows the location of the various 
plug- in units and chasses. 





Table 8.1 

PLUG- IN WaTS 




Nur-iber Used 


Name 


V/ir ing 




Test Charts 


30 


Transceivers 
Pulse Boosters 


, — , ^ 

PX-5-147 

PX-11-115 


PX-5-129 

1 


3 


P)U11-125 



8.2 Operation Test 

An operation test is described in section 2.6 of the operating 
manual. The actual test cards (v/ith nines punches) should be used here 
since (due to the "1", "E", WE'", and '•4« channels) the constant transmitter 
may operate correctly with certain numbers but not others. 

The various program controls can be checked by repeating the 
above test and successively using different program controls. 

Note that the PM circuits of groups Jjj^ and K^r were originally 
wired so as to provide tho correct pulse autanatically. This would moan 
that negative numbers would be set up as complements with respect to 10^-1. 
The various manuals instruct the operator to set up negative numbers as 
Gomploments with respect to 10 , This means that tho tubes A' 29, A'30, A'70 



VIII - 2 



Tablo 5,2 

GRASSES- AlID RELj-iY CIRCUITS 



Name 



Top 
Gato 
Top 

Gate A 
Gate B 
Gate C 
Gate D 
Rolay Strip 



Panoi 
1 
1 
2 
Z 
2 
2 
2 
3 



Position _ 

" Tubcc" 



1 and 2 
41 - 60 



1 and 2 
10 - 20 

21 - 40 
41 - 60 
61 - 80 



Wiring 

PJUll-lOlA 
PX-11-104 



PX-11-lOlB 
PX.1U108 
PX-1 1-109 

PX-1 1-110 
PX-11~111 



PX-11..118 



Static 
Test Charts 

PJUll-121 



Dynamic 
Tost Charts 

PX-11-.122 



PX-11-123 See note 

below 



Note that there is no dynaniic tost chart for panel tv;-o. These 
circuits, being rolay controlled, operate too slov/ly to be 
observed on an oscilloscope. 



VIII - 3 

A' 71 
and^should be removed frcan the constant transmitter. Note that these tubes 

are shown on tho v/iring diagrams but not on the block diagram, PX-11-307. 

8 . 3 Possible Failures in Constant Transmitter 

Possible faults, their probable causes and cures, are listed 
below. 

a. Failure to transmit anything on one digit channel, regardless 
of group used - chock corresponding column of tubes on gate 
chassis of panel 1 (see cross-section). 

b. Erroneous transmission of one digit in a particular group - 
check corresponding matrix gate on panel 2. 

c. Erroneous transr.isnion of one digit in eoveral groups - 
chock corresponding pulse gate inverters on panel Z, 

8.4 T he IBM Reader 

If tho operation test shows failures ¥/hich are not caused by 
tube failures such as indicated above (section 8,3) then the relay circuits 
should be checked. 

A crank can be used to slowly turn the reader through a card 
cycle and someone can vmtch tho coding relays GC-j_ to Cg on the schematic 
diagram on PX-11-116) and the digit i-elays (see PZ-1 1-309). 

If all these relays operate properly but tho constant transmitter 
does not transmit the proper number then the gate ohasses should be rochocked, 
and perhaps a static test (using tho static test chart) is indicated. 

If the coding relays do not operate properly check the coding cans 
in tho reader (or call an IBM service man to do this). 



i 



VIII - 4 

Also chock the IBM reader plug-board for a loose connection in 
case of failure in one channel. 

For general failures in the IBM reader call the IBM service man. 
In all such cases it is the responsibility of the raaintenanco personnel 
to definitely locate the failure as bein^'r^ in the IBM reader proper. 



*ye/^pe//(y^ ryff/j.o^^^o^y9J./y/ T^pJl/sysr/i^y^ J^^^^-^SCVfip 



D 

a 
















Ct:. 
[15- 



-V; ' 



_<c 1 



Sil-ll -Xd -^goo&Wl 



^■^ 



5 









CM 



^ 
Q 






I Ui- 



1:3 

>Z1 



-<^ 






-Ui 1 

±iZ] 



f 



/ ifsii MifP' ^s y^y 'fmz I iroa/M^ n/j^ 0^ . 









:^i: 



I 

V3 






\ 

I 






\ 



k- 



I 

K 
k 



\3 

I 









>^^n~^ 






•<) . 


N 1 




5 


//- 


■n 


5^ 


1 1 


1 ^ 


H^— 


1 s 


<0 — , 


^ 


Iti — , 


r\ 


^ 1 


\ ■ 
1 — 


^ — 1 


1 — 


fl^ 1 




•j.soo^ -^ 






^as. 



4 



^ni 



I 

I 



k 



I 



^ 



M 

Hi 

k 



5 









^ 



k 



k 



I 






I" 

k ' 



0; 
1*4 

o 



I 

o 






It 
o 

ft: 



J 



"1 

N 



V 

^ 

^ 
^ 









^ 
^ 

^ 



.1 



S 



«00R£ SCHOOL Of ELECTRICAL ENCIWEfRINC 
UNIVERSITY OF PENNSYLVANIA 



MATERIAL I Ftt^SH | 5CAIC 



Oravvn by: 

CJMcC 

^1— i*M I I II III ■ II 



1^ // 



AoorovcKi by : 



PX-U'301 



IX - 1 



IX. THE PRIIOTER Aim IBM PUITOH 



^•1 Circuits of the Print er_ 

The printer contains no plug- in units. Tho gate chasses and rolay 
circuits aro listed in the follov/ing table. 



Name 



Gate A 
Gate B 
Gate C 
Gate D 
Relay Strip 
IBM Punch 



Pos it ion 
Fanoi 



Table 3,1 
PRINTER CIRCUITS 

'.7ir ing 



2 

2 

2 

2 

1 and 
3 



Tubes 



3 
21 

41 

61 

1 



20 
40 
60 
80 
80 



PX- 12-104 
PX-12-105 
PX-12-.106 
PX-12-107 
PX- 12-103 
PX-12-112 



Tost Charts 



Statics 
PX- 12-111 



9»2 Test Proc edu re fo , r tho Print ey , 

Inspection of PX--12-307 shows that the printer contains a tube for 
each digit in each column of the card besides the PM circuits. This means 
that any systematic check of the printer must involve tho transmission of 
all possible digits to all the accumulators (or master programmer) from which 
printing is done and a card printed after each transmission. Since it is not 
adTi«ablo to punch the same number in all columns of a card a testing 
sequence similar to tho following is suggested. 

Cards should be prepared as follows. In some ton digit group, say 
corresponding to Alr, in the constant transmitter, tho following numbers 



IX - 2 

should be punched, 

(1) P 0123456789 

(2) P 1234567890 

(3) P 2345678901 

(10) P 9012345678 

(11) M 0123456789 

Theso cards arc then placed in the IBM reader and the programming 
arranged as follows:. 

1) IBM reader roads the first card. 

2) The numbers of A^j^ axe transmitted to all accumula.tors which 
participate in the printing. It is also suggested that at each 
card reading ouo's bo transmitted into all docados of the 
master programmer which pai'ticipate in the printing, 

3) The printer prints the number in the accumulators and the 
master programraor, 

4) The accumulators ars selective cleared, 

5) The process repeats until all the cards have boon read. 
Note, that if, duo to the typo of problem on the ErIIAC, it is 

inconvenient to selective clear all the accumulators involved, the cards for 
the reader may be prepared as follows* 

(1) P 01234 56789 

(2) P 11111 11101 

(3) P 11111 11011 

(4) P 11111 10111 



(10) P 01111 11111 

(11) P 11111 11111 



IX - 3 

The cards punched in the above test may be compared visually or 
they may be compared v^ith a standard set in the reproducing punch. 

9 . 3 Types of Fa ilure and Rom ed j y 

1) Failure of motor generator on punch 

a) Check a^c povrar supply* 

b) Check intsrcomiect ion to ENIAC. 

2) Failure of punch to operate when programmed. 

a) Card magazine empty. 

b) Card hopper full. 

c) Failure of starting circuits in initiating unit. 

(see Chapter II), 

d) Failure of starting relay in printer (PX-12-103). 
o) Failure of punch starting circuits (PX-12-112). 

3) Punch continues to operate. 

a) Starting circuits in initiating unit (see Chapter II), 

b) Check reset cam in punch (PX^12-112). 

4) Punch operates but fails to feed a card. 

a) ChcjoL condition of bottom cord in. magazine, . 

b) Possible mechanical failure in feed mechanism. Call 
IBM service department, 

5) Punch fails to punch card. 

a) Inspect digit relays (PX-12-103) back of panels No. 1 
or No. 3 to see if these pick-up. If these pick-up and 
card is not punched then failure is in IBM punch or 
interconnection cable. If these fail to pick-up then check 
starting relay (PX-12-103) and interlock cam. If those 



IX - 4 

pick-up but fail to hold check holding cam. 

6) Pails to punch in a particular column. Chock tho corres- 
ponding tube, rolay, or jumper connoction on plug-board* 
(Sgo Pi-13-104 to 107 1 PX-18-103, P3C.12-.3054) 

7) Multiple punches in some columns. Chock against multiple 
program pulses circulating in the ENIAC, Chock tubes in the 
associated columns k 

8) Intermittent extraneous punchings. Chock associated relays 
for spring tension. Vibration may causo the rolay to 
gradually pick up. 



n 



Groups 9 to /6 
To Ace. an M.P. 



G/foups I To B 
To Ace. o/f M.f? 



Relay Stp//= 
PX - /Z - /OJ- 

7 A/ T e^ C OMAJf:C T/O N 



S! - 



B L ^ N H 



Printer Gate 
Unit ,^ 
p>:- /Z - /04. 



G ATE Unit 8 
PX'/Z I OP 



.,w 



Gate Unit C 
P/-/2- /O^ ' 

:-< Pp. cKT- Panel 
P/-/Z-//0. 



Oats U nit D 
PK~ I2-/07 



PM pt 
oe AC 



L _..._,_ 



TEii^,V5roR/^£-/? Unit 

PX-/2 -/oa ■ 



« 



Pel/^/ Sr-/^iP 



W / R / N G 

PX - U - I 



03 



j / f^T E f? C O N ME CT/ON 
(yJ J F? I A/G 

PX- /^ - lOZ - 

pRONT P^rjEL 

PX ~ />a - / Gz 



I PTE RCO/^N E CT /OM D / /) G PP P7 Op PPJNTPR 









«\1 






MOORE SCHOOL Of ELECTRICAL rMOIMECRINO 
UNIVERSITY OF PhNISSYLVAMU 



Printelr Interconnection Di^gr/^m 



MATERIAL 



Ftr^SH 



SCAi.f. 



/ 



/ 



Drawrt Oy; 

CJp-JcC 



ChwcMsd bv 



/ 



^ 

C^^"^^ 



4- 3>'4S' 




^ocoveo by 



PX-12-304 



- 1 



X. MASTER PROGRAMMER 



10,1 Circuits of the Master Programmer 

Note that 10 of the master programmer transmitters are located on 
the cycling unit, see PX-1-301. The following tables give a list of the 
plug- in units and chassiB circuits of the master programmer. 







Table 10,1 

PLUG- IN UNITS 






Number of Units 


Name 


ViTiring 


Test Charts 




20 


Decade 


PX-8^101 


PX-8-125 


10 


Program 


PX-8-103 


PX-8-123 


10 


Pulse Former and 
Carry-over 




PX-8-104 


PX-8-124 




20 


Transmitter 




P3U8_105 


PX.8-122 

— 


fa—- — ' 


10 


Stepper 


PX-8_112 


PX-8-126 




Static: 
PX-8-120A 
PX.8-120B 
PX.8-118 

Dynamic : 
PX.8-121 



^Note that the two panels of the master programmer are identical in their 
functions. Thus the gate chasses are identical on the two panels. However, 
the plug-in units arc not arranged the sai.ie, some being on the cycling unit 
panel. 



X - 2 

10. 2 Operation Tests 

Most tests can be niado using only the initiating pulse. 

a. Initially clcar» Pood initiating pulse into each decade direct 
input in turn. Decades should step once for each pulse. If next 
decade to the left is coupled to the one being pulsed, it should 
step once each time decade being pulsed goes from 9 to 0. ViThen 
decades associated in a group register number set on top row of 
decade switches, they should clear on next pulse. 

b. Make soaio test on steppers, using stepper direct input. Check 
operation of stepper clear sv/itch by sotting to various positions; 
stopper should count up to position corresponding to switch 
sotting and thon clear back. Since cloaring is done by CPP only 

1 add time after coincidonce, it appears to be caused by pulse 
which puts decades into final position. 

c. Chock stopper direct clear input by first running stepper up 
to some stage other than first, as in (b), and thon pulsing 
stopper direct clear input. This should clear stepper. 

d. Chock overall operation of each stepper by feeding pulses to 
regular program input. Decades associatod with program in use 
should register each pulse, and after a number of pulses equal 
to number set on top decade switches , decades should clear and 
stopper move up. Similar action should take place for each of 
tho six stopper stages and each of the six corresponding sets of 
dccado switches, 

«, To chock outputs, use same procedure as in d, , and feed output 
to another program input. Output pulses, one for each input pulse, 



X - 3 

should be obtained as long as stepper is on stage corresponding to 
output being used; when stepper mo7es up, pulses should be obtained 
from next output, etc, 
f. If it is desired to chock operation at normal speed, a continuous 
program can be set up using tv/o selective clear transceivers, feed- 
ing output of each into input of the other, and use this scries of 
pulses in tests d. and o, above. Outputs may, if desired, be 
observed on oscilloscope. 
10,3 Trouble Shoo ting: 

Several possible faults are listed bolov/, together with their probable 
causes and cures, 

a. Decade or stopper fails to cycle and will not cloar to first or 
zero stage - replace decade or stepper, 

b. Decade clears but does not cycle - replace pulse former - carry-over 
unit, 

c. Decades initially clear but fail to clear on reaching ooincidonco 
with switch settings - check ooincidonco gates, parallel gates, 
stopper output inverters; if none of these are at fault roplaeo 
program plufj-in unit. 



XI - 1 



XI. ■ A.C. EQUIP;.iElIT AND ?0\'>!ER SUPPLIES 

11.1 Introduct ion 

This chapter covors tho following topics: 

1) A.C. power and control systom. 

2) Starting sequence. 

3) Power supplies, bleeder, and condensers, 

4) CoiTmon failures. 

5) Ventilating systom raaintonanco, 

11.2 AifC , Po wer and C ontr ol System 

The complete diagram for the- power and control wiring is shown on 

drawing PX-l-lOl. Tho rack from which the A.C. power is distributed to 

the EiJIAC heaters, to the fans and to the po\ver supplies is shovm on PX-1-304, 

Simplified v^iring diagrams of tho povrer sj'stern and control circuits are 

shovm on the following! 

P.X-1-303 Power System Block Diagram 

PX-9-.307 Cycling Unit and Initiating Unit 

Block Diagram. 

11,2.1 Puses 

Fuse sizes are sho'/m on the drawings as follows: 

A.C. Main Fuses PX-l-lOl 

Power Supply Heater Puses PX-13-111 

Povrer Supply Plate Fuses PX-13-111 

D.C. Circuit Puses PX-13-102 



XI - 2 



These d-c circuits and the pov/er supply heater circuits use 
■'.¥est8rn Electric alarm type fuses in the following sizes: 1/4 amp, 1/2 amp, 
1 1/3 amp, 2 amp, 3 ainp, and 5 oinp. In certain cases (those narked 5S on 
PX-13-102) the 5 regular ampere fuse was found to be inadequate. Western 
Electric Company does not manufacture those fuses in larger than 5 ampere 
rating. The 5S fuse is made by refilling a 5 amp. Western Electric fuse 
(catalog No. 35H)with a nev^ link of Advance alloy round wire, 0.0126 inches 
in diameter. 
11,3 Starting Sequence 

Drawing P}:~1-112 is a chart designed to aid in locating troubles in 
the main power sources which may develop during either the starting operations, 
or during running operation but affecting the main powor sources or 
auxiliaries (fans). 

Jn using the chart it should be remembered that since each step 
is dependant on the previous step, the point at which the sequence fails should 
be determined so that possible troubles beyond that point need not be 

investigated. 

When trying to locate trouble vfhich has turned the entire machine 
off certain safety switches on the a-c distribution panel should be opened. 
This prevents any testing (by going through portions of the starting 
sequence) from subjecting the tubes to numerous heating and cooling cycles 
(which would increase the probability of failure of the tubes). If this is 
done certain protective relay circuits may be shunted for testing purposes 
without endangering the ENIAC. Furthermore, the control wiring, contactor and 
relay adjustment, and entire starting sequence may then be tested without 
turning the main power on provided the under-voltage release and phase 
failure relays arc shunted. 



XI 



11.4 Fowor Suppliss. Bleeders . and Condonsers. 

The following drawings show thy wiring from tho a-c sources shown 
on PX~1-101 through the power supplies to the point v/hore th- d-c terminates 
at each unit as noted. 



11.4.1 Supplies 

PX-13-104 
PX^ 13-108 

11.4.2 Bleodors 

Pa-13-106 
PX-13-112 
PX-13-10 2 

11.4.3 Condensers 

PX-13-102 



Statidard Pov/er Supply Wiring Diagram 
Povrer Supply and '.Viring Diagram 

Power Supply to Bleeders Inter coi-inect ions 

Bleeder Wiring Diagram 

D_G Voltage Chart (shows blooder to d-c 
panel connections) , 

D-C Voltage Chart (shows d-c panel to 
condenser connections) 

PX-13-109 Power Supply Condenser Wiring Diagram 

11.5 Co m-non Fai lures 
11.5.1 D-C Undervoltage 

If, after attempting to turn the d-c on by depressing the d-c 
start button, the d-c trips off at the_.end_ofLJLhe„10,..seconl_ ln i, tia l clea ri ng, 
period . usually the trouble is caused by an undervoltage from one of the 
28 power supplies (undervoltage in supply Z vail not trip d-c). Proper 
procedure to locate trouble is as follows; 

1. Turn d-c on again by d-c start button and check power supply 
fuses by observing neon lamps in top of d-c fuse cabinet. 

2. If 1. does not detect the trouble, place a .jujaper across the 
series stop circuit which runs throufih the undervoltage relays 



b 



XI - 4 

(relays are located in one of the by- passing condenser 
cabineta). Turn d-c on again and note which relay fails to 
hold when pick-up relays drop out. Caution: 1500 volts d-c 
potential on so:ne relay contacts. Check corresponding pov/er 
supply for a tube with a faulty heater. Caution: After replacing 
a power supply tn.ba alJow 1 minute warra-up time before turning 
d-c on. 

3. If no tubes are faulty check line fuses in power supply fuse 
panel, by renioving pull-out block, and tostin^ with an ohm- 
metor, or so;ue other oojitinuity chackinp. device. 

4. 2£_Jiot forget to remove jumper across undervoltage relays, 
11.5.2 D-C Fuse Failures 

Quito frequently the operator forgets to sot the pperation switch 
on "Oontinuous''boforc turning on tho d-c. This will result in the blowing 
of a d-c fuse. 

Locating a blown d-c alarm fuse is usually not difficult, for these 
fuses have indicators which stand out whon the fuse has blovm. Occasionally, 
however, tho fuse wire may stretch, but not break (if it is operating near 
its rating) permitting the alarm contact to close and tripping the d-c off. 
In such cases, a persistant and close inspection may be required to locate 
tha offending fuse. The correct sizes of fuses are shown on drawing PX-13-102. 

Under certain conditions, on turning ox\ th® 'd-c the machine will 
trip off befors--complotion of the 10 second period due to blowing a d-c fuse. 
■'■'he blown fuse may be caused by an undervoltage in one of tho d-o supplies, 
and it is suggested that this possibility be investigated before assuming 
that tho trouble is in one of the ENIAC units. 



con ^anr>(,( 



(^ 



C3 

220 



HO 



?''C 



t^£i/! y o/" 
CaA/r/?c TO •€ 



/!oxtc //?-«'/ ^^if) y 



- £A///?C J^ffM 



220 £-.^»f.' CaAJT K. 



fi/^aen ^'i-oT iT. 






/Sox a/" coAjrtTCrajp 



STfi/ir Push Bottom 
/Vft-ur P/^/utL See 



/^^c»/Aje/e / I/) 3. 



■f.C. /Jj-iT^/Si/T/aAJ ^Mctr. 



^/u/T/ffT'M<} UMir 



Ci^as /*J O O/^ 



^3 



/94 



//<rdo Tiv^a 7»fss 



s, 



p. 



irofi Puju Burrou 






/?4 



/^ <i S S y a c 



S C ,-^ iJ ^ £" Cl /^ 



(J) 






A C. Otjreisur/ou ^^cn. 

/A/tT. U/JtT-Slff)fi-30Z 



San "f ^.a/uTncro^ & 



Mo to ConrftcT^ 



/^f>CM. Las. - CoAjT'e B 8ot 



do 



/€ <£• /<? .J? ,C 4' J- 



Z20 



P. Pan/£^So/>f>iies 



f). C. Otsre/Q oTit Mantle 



S, 



Q, 



Payurm Sa/»/»iv HfATtR /^fj£ Pn/Lu^f - Sef c? SCco-aj 



E. 



fJ.C.Dis TKieuti ouKucK. 



no 



t M inure TiMe/i 



D. 






eV /'ayue^ Sou/its 



do 



P^Ajf> "Ti oea/i O'-'T <S>^ ^eOftr/O'M Tk CO'/a a/'-ye/frfO yo:.rp^ 



D. 



210 



Pe»re ^(hjthcToi^ 



PViVcM'Mfjt^i' i. 1 a 



r, 



p, 



I, 






Pp/ZtQO. 



dc 



220 



H ■ //UiT/fH. 



^. C D'S7iei9in>»u P'fKic 



'-7, 






220 



Jiojec Ti.-^ee 






A-t 



c/o 



ZZO M u.V.Pxic Up 



3y P/i>- ChMOfAiiOiC/is r 



i3> 



A^ 



r/o 



\220 



fC' /9i/i^/i//>ey 



\8«X ^e eout'K. a. 



<5/ 



c/o 



J, 



H, 



do 



/Mni»L (^UOK Push BuTTatt 



/A.-iTi/ir'*'^ ^'ifir 



P'/e.Cjs/jue, /A/J7-//ri. Cc<F/P/^ P'^i^/ S<jrToAj C/fdjSa^s <Ste^ir^^ 



C^^etreAj p.i.tir I 'u,rtfirjAj^ ^aj it 



*r. 






Sax o/' t^OAir 'yS ^ 



110 \ 
I/O \ 



ffv>f/u»py ^ft»y 



Ml: ^.>TC/ai''-"-i^ 






4^^00C wH//7CV^J 



43 TWe/e/^osTffrj 



Oue/efifftT/AJ^ e^uieo Sy.' / • ^/>ery ^'iT&«^, ? /2*'/v7/'<r^ /ic 



Pay o/' ^oo^ iPo i^Kyr 



Ti/^^oj^A/e^iy SAiu/jre o 



/AJ Pucr h/oifK /Seoi'C 
S*c/f Cai/t 



P-/>uiiY^vii>C'''«r^ T/mx. 



C^ 



o 



S^e £f/)jaA^s Pa-e C fiao^P 



.IP />IST/?/SClT/3jv PdCl. 



/lO 



I/O 



//Lt 






fi.C.Sraf> Poin Svrr,^ 



OP SrfiJir PvjM SjrTaAt 



j?£ipy 



..Vo 



/^.C-^iav^ ^va Atiftii 



AJ, 



L: 



Si£ /Ci/fsOA/i Poe /., OfPoJ/rt <ir X^aaiy^ 



do 



£ei:/fy A AJ^r /PiS^A^/i'i.i.y Pycxso zJ/3. 



Cut- Of r ^ei^y 



Jo 



A/ 
Pt'X't infiy 
^rc/jy 



da 



PS. ,^fy>T-£e -A'/yf."? 
fvie /^£i»yj 



<?z 



O.C 3Tn/er PtiiM Si^rraM 



"oyu^jc SuyytfS.i yVrjfrf/^j ^£/f/iy>^ /=i»j<r /y^/cwee 



do 



y9ii PP^r.e .■^^<r/e ^^ /ft/royj'.^rycmt/' Ti'^ytye-D <yy^ 75 /'p.ey^/rSyfPe' 
^pPi^<:e^<'ey<JP 3/- /i/j./c-ti^si:' or J'^/srp J'iii/yr<:jY A^c^rcXi/^/^fAJDiSD. 



^> 



olS ■ 



^ogfOaut Pi'x CO - Oty 



0.C. Juose V*iry>t,t ^(l»« 
PS htm; fniivtt /^icaysQ 



/^/ICHfMfl^Y /■'^O. 



P'aitye/e Py'ct/ize ae y^yyyyu P'ittrc Puse -**.«»v>vj 



Co/uo£AJseit <^y?e'r 



/ICOisT/l/et/ryoyn £/9c K 



(3) SacM C/oajes Pj O^c^ Cnzzurr .P^c^e Ta Sjsok£/\j jc/yjee^i^ OyAryox Pyrr£o 

Paj P^i'<MJAi^ypy ^y^a ) U'Lc C^yfojP /'^jCCM'4iC To Jrofi, ypyfya/^e Ctr 
@ P?/^ae>p/'urr OtJr or C P^Siyify /,r /y<yx>i<y?rfyi £y PS fa ^*Jif //tiMr- ife'if 

p>x-/-3a4.. 



MOORE SCHOOL OF ELECTRICAL ENGINEERING 
UNIVERSITY OF PENNSYLVANIA 



£A^/y^C Sr-/?ye r/,^j ex ^6 <p ^6/^^ c'z 



SCALE 



DRAWN BY 

'iCci/^/^w^s. 
4-3 -41: 



CHECKED BY 



APPROVED BY 



PK^HE 



XI - 5 

11.5.3 D-C Undorvoltago Rolcasc Relays 

P3C-13-113 shows the Oonnoctions and arrangement of these rolays 
which are located in the by passing oondonser cabinet and connected to the 
d-c at that point. 

11.5.4 D-C Panel to ENIAC Units 

PX-13-102 D-C Voltage Chart 

PX-13-107 Chart for D-C Wiring in Power Trough. 

This chart will aid in dotorrnining what 
voltage appears on each terminal of the blocks 
loc;at-=d in the power wiring trough. 

PX-13-115 A and B D-C Tiring in Power Trough. 

These drav/ings enable one to trace each voltage 
from the panel to the various terminal blocks 
at the ENIAC units on which it appears. 

11.5.5 Replacement and Design Data 

PX-13-103 Power Supply Drains 

PX-13-104 Standard Power Supply Wiring Diagram 

PX-13-108 Power Supply Z Wiring Diagram 

PX-13-109 Power Supply Condenser 'firing Diagram 

PX-13--110 Keasuremcnts on Chokes 

PX-13-111 Power Supply Data Chart 

PX-13-112 Bleeder Wiring Diagram 

PX-13-114 Pov/or Supply Specifications 

PX-13-116 Power Supply Replacement Part Test Data. 



1 



XI 



11,6 Ventilation Systom 
11.6.1 Pans 

The fans used in ventilating the ENIAG are American Blov/er 
Utility Sets No. 250C. 

^« Speed Ad^-iu st ment . 

Each fan unit is equipped with adjustable motor sheaves. The 
speed of these units may be increased by adjusting the motor sheave until 
the desired air delivery is obtained. To increase the fan speed (correct 
speed is 770 RPM) the movable flajigo of the motor sheave must bo turned 
toward the fixed flange. An Allen -wrench is provided to loosen the set- 
screw locking the- flange. After the flange has boon turned the roquirod 
amount, tho sotscrew should be tightened locking the flange in place. 
Caution: The flango must bo in such a position that the locking scrow 
rests on the flats and not on tho threaded protion of tho hub. If nocossary, 
the bolts should hz adjusted as described below. All set screws should 
bo carefully chocked and tightened at least four times por year. 
2. V-3olt Drives 

Bolt tension should bo just auff ioient to eliminate excessive 
Gag on the slack side. To adjust the bolt tonsion loosen the bolts holding 
the motor mounting plate to tho vibration dampencrs. The mounting plate 
may then be moved vertically up or down to the desired position and the 
bolts tightonod. On unit. Model No. 250G, tho motor may readily bo moved 
horizontally for minor bolt adjustments. 

To replace b.lts, romovo tho bolts from the sheaves, then remove 
the bolts from the ends of the bearing support, tilt the bearing support 
member until belts can be removed and the replacement made over the ends of 



I 






XI - 7 

the support member. Belts may also be replaced by removing bearing cap and 
pulling belts through the shaft hole in bearing support. 

The following are typical V~Belts to be used for replacing belts 
which may become v/orn or may break: Dayton A38 , Thermo id No. 1400, Brovming 
VR.'uFHP-138. 

3. Motor Bea ring s 

The fan motors sxe provided with ball bearings. Ball bearings are 
filled with grease before leaving the factory. This grease should be re- 
plenished each six vnonths. 

GreasG should bo applied to tho boaring from tubes -ivhich may be 
obtained from the Pafnir Bearing Co. or local ball bearing distributors. 
High pressure grease guns force too much grease into the bearings and through 
seals and therefore should not bo used. Use only grease having the follow- 
ing general specifications; 

1. Consistoncy a littlo stiff or than vaseline maintained with 
minimum change over anibient tcmporaturea oncountorod. 

2. felting point preferably above 150 C. 

3. Freedom from separation of oil and soap under operating and 
storage conditions. 

4. Froodom from abrasive matter, acid and alkali. 

The following greases or equivalents are rocaamended: Keystone 44, 
Master M31 , Alemite 38. 

4. Fan Baarin gs 

Pans are equipped with self aligning slseve bearings of the bronze 
bushing typo. The oil is distributed by means of graphite packed oil grooves. 
Do not remove this graphite. Do not insert any piping or pipe fittings 



XI - 8 

bctwoon oil cup and bearing. Pill the bearing with a good grado of mineral 
oil of SAE viscosity No. 40. To fill tho oil reservoir of fan bearings, 
place nozzle of oil can in the bottom of the oil cup, forcing in the oil 
until tho reservoir and cup are full. Per room temperature 100° P or above, 
USG SAE No. 50 or 60. This type and grade oil is the some as used in 
automobile motors. Inspect bearings at least once ev;.ry 30 days, 

5» Pa ilurc 

Should a single fan stop, this v/ill probably bo caused by a fuse 
blovfing in tho fan circuit. These fuses are located in the fan panel - 
sac draY:ing PX-1-304. The fuses used to protect the fans from overloads 
are special, but readily available. These fuses arc Bussman Manufacturing 
Company's 6.25 amp 230 Volt Cartridge Type Pusetrons. Only fuses having a 
thermal time delay charactoiristic and rated at 6.25 amperes should be 
used for these fans. Otherwise all motor protection (danger of burning- 
out windings) is lost. Another acceptable fuse is Shawmut Manufacturing 
Company's "Therm at rip". 

Should these fuses blow a second time after having just been 
replaced, tho motor should be inspected for causes of overload such as lack 
of oiling, worn bearings, tight belts, etc, and for grounds. 

All fans stopping at once may bo caused by a failure of the fan 
source of power caused by fuse operation, or manual opening of one of the 
circuit safety switches located on the a-c distribution rack and in back of 
the machinery laboratory switchboard. Pan power is unregulated and is 
separata from ENIAC povz-er - sec PX-,1-101. 



XI - 9 



11.6.2 Air Filters 

The air filters used in the doors at the rear of tho ENIAC aro 
"DuEtop'* air filters as manufactured by tho Ovrens -Corning Pibsrglas Corp. 
Similar filters by other manufacturers may be used but care should be taken 
to select a filter v/hich uses a fireproof adhesive similar to the Lindall 
adhesive used by Owens-Corning Fiborglas Corporation. 

Two sizes of filters are used: 10" x 20" x 2", and 20" x 20" x 2», 
tv/o of the forsaer being used only in those places where one 20" x 20" x 2" 
cannot be conveniently installed, i.e., in the bottom inlet on the two 
inlet doors, and in the two bottom inlets on the three inlet doors. 

In the Moore School installation the 20" x 20" x 2" filters are 
also used in tho fresh air inlet chamber. 

The frequency of changing the filters depends on prevailing dust 
conditions and can best be determined by examination and experience. An 
indication of the filter's condition can be obtained by the temperature 
guages in the ducts above each unit. With new filters, the tomporaturo 
rise in each unit will bo approximately 11° F above room ambient. Should 
a considerably larger rise occur, and visual examination of tho filter 
indicates that they are quite dirty, thoy should be changed. 
11.6.3 Door-of-Unit Dampers 

Those dam.pors aro those which adjust the flow of air through the 
above montionod air filters. Tests have proven that for uniform temperature 
to exist within the cabinets, 75 ^o of the air should enter through tho 
lower intake, and 35 % through tho upper. The dampers should bo adjusted 
accordingly, with the fins of the dampers so adjusted as to drive the 
incoming air toward the bottom of tho cabinet. All fins of ai^y one damper 



I 



XI -10 

should aGsuin'3 tho same angle so as to insure the uniformity of the filter's 
dust coll'iction. 

11.5.4 Rocirculating Dampers 

Tho ventilating ducts are arranged with automatic dampers which 
tend to koop the ENIAC room at tho tomperaturo set on tho controlling thermo- 
stats (tho two thermostats which arc set on tho building wall behind 
accumulators 9 and 15). The dampers are so arranged that when the room 
temperaturi5 rises above thermostat setting, more air will be exhausted 
to the outside and less into the room and vice versa. 

The wiring diagram for this system is shovrn on dravdng PX-1-101. 
The manufacturer's (liinneapolis-Koneyiyell Regulator Co.) catalog numbers 
are also given on this drawing. In the diagram shovrn it may have been 
necessary to interchange the 3 and "T wires to obtain proper operation. 
The location of the damper motor circuit fuses is shown on drav/ing PX-1-304, 

11.6.5 Service Required by Recirculating Damper Motors 

Inasmuch as all moving parts of tho damper motor are immersed in 
oil, periodic lubrication is not necessary. Tho cover should be left on the 
motor at all times to protect the motor from dust and mechanical injury. 

It should be noted that tho balancing relay armature is adjusted 
to "make" contact on ono side when the relay is do-enorgizod. 

All sot scrows on the motor-to-damper linkages should bo chocked 

once oach m.onth. 

Listed bolov; are causss and effects of certtxin conditions which 

may exist in tho control circuit. 

1. Broken red wire or blue wiro in control circuit: l-Iotor will 
run to tho closed position and stay there. 



i 



XI - 11 



2. Brokon vfhitc v/iro in control circuit: Motor Vidll run to the 
open position and stay thrc. 

3. Loose or dirty contact on control potent iornotor : Motor will 
run to tho closo position when the v/ipor on tho control 
potentiometer is ^.t a position v/horo a poor contact is 
cstablichod. 

4. Insufficient voltage: The sensitivity of tho control circuit 
will be reducod, and tho power of tho motor will be materially 
lessoned by a voltage drop, 

11.6,6 Room Thermostats 

got-ti^-S J>^- fiP P"* The r mo s t ats . T-92A - Turn temperature sotting 
screw on top of therraostat until indicator points to tho desired average 
room temperature on the scale. 

Ad iuct nient of Room Ther mosta ts, Factory calibration - All 
thermostats are carefully calibrated at the factory aiid no attempt should 
be made to change any adjustment othar than those mentioned under "Setting" 
miless the thermostat is found to be out of calibration after being in 
actual operation for several hours. 

Thermostats ^-ith non-adjustable differentials (TS2A) aro 
calibrated so that the sliding contact is at the center of the potentiometer 
coil when the room temperature is equal to the sotting of the indicator. 

Care must be exorcised in checking tho adjusr/mont of those 
thermostats sinco heat from the potent iom.^ter coil afiects the thermostat 
calibration and the reading of the cov^r thormometor (if used) to tho extent 
of about 3°. Tho thermostat should therefore not be checked urrtil it nas 
been in operation with the pov.-.r on and with the cover in place, for at least 



XI - la 



an hour. To check the adjustrsicnt , (this should bo done as q^uickly as 
possible, before the heat from the potent ioraeter can be dissipated, and to 
prevent hoat from your hands or breath from affecting the calibration) 
remove the cover aiid sot the indicator to the room temperature as indicated 
on the cover theriiioinetor or other reliable thermometer placed near the 
thermostat. Then observe vriiether the sliding contact is in the proper 
position (pee preccdins paragraph). If it is not, turn calibration screw 
(on bottom of thermostat) to the right or loft as necessary to correct 
the adjustment (turn to the right to move slider to the right). Each 
11/8 turns is equal to approximately 1°. 
11.6,7 Thermostats for EIIIAC Protection 

These tompurature controllers are of Minneapolis-Honeywell 
Regulator Company's manufacture and are rated as follows: 

Remote Bulb Controller 

Catalog Ho. T-615A 

Rango +65° to 140° F 

5 ft. Tubing with Bulb 

Me thod of Sottin g; nnd of AdiustinK 

at top of box . iA ^p -hv^r. 

1. Turn adjusting scrow^until the indicator on the a-utside ol tne 

case is opposite tho dosircd "cut-out" tomporaturo. "R to W" contacts 
make, on tomporature rise - "R to B" makes on tomporature fall. 3calo 
divisions are marked numorically. Each Faronhoit division (on the loft) 
oquals 10° tMid each Centigrade division (en tho right) equals 5 . T'ho 
notations "L" and "H" roprosont the low and high end of the scale rang-o- 

2. On T615A Controller, tho differential bctv/ocn cut-in and 
cut-out temperatures may bo increased by turning adjusting screw to the 



XI -13 



right, v/hich raises the indicator from "A" toward "H" on tho differential 
scale. The equivalent number of degrees for each division from A to H 
varies v/ith each scale range and with the point at which the indictitor on 
the main scale is set, Tho approximate values hoYrovor are as follov/s: If 
tho main scale indicator is sot near the low end (65° F) each division 
from "A" to "H" equals approximately 3 V7°. at tho high end each division 
equals approximately 1 3/7°. 

For direct acting controls, tho cut-in toraporature plus tho 
differential equals the cut-out tomporaturo, and for rovcrso acting controls, 
the cut-out tsrap&rature plus the differential equals the cut-in temperature. 

Mercury Switch Adjustment: If the operating differential of tho 
controller is considerably smaller than that for \Yhich tho indicator is 
sot, tho mercury switch may bo out of adjustment. This sometimes occurs 
when a broken switch is replaced. Before making aiay adjustments, however, 
bo sure that the difficulty is not due to the controller boing "off level." 

Note the level indicator. 

The adjustment may be chocked as follows: Sot the differential 
indicator approxim^^toly at mid-scale, and the temperature indicator so 
that the operating lever rests lightly against its upper stop. Pross doi,vn 
on the left hand end of the operating lever until it is about midway 
between its upper and lower stops and just touches tho differential lover. 
This movement should not cause the mercury to change ends in the switch. 
Further downward pressure on the operating lever vrlll force it to the 
lower stop carrying the differential lever with it and will cause the switch 
to tilt and shift the mercury. Now, allow the operating lever to slowly 
return to midway between stops and note that the mercury should not shift 



XI - 14 

its position. Allov/ the operating lever to return to its upper stop and 
the switch should tilt back to its original starting position. 

If the switch does not oporate in this manner, turn the eccentric 
screw slightly to the right or loft as nooossary and re-chock as outlined 
above. 

To Replace Mercury 3v/itch: Note that the arrangement of tho 
contacts and flexible loads and make sure that thoy are in proper position 
when the new siivitch is in plaoo. Use the point of a knife to pry tho 
sviTitch clip loose from the mercury switch - never attempt to break it loose 
with your fingers. Wrap two layers of friction tape around the switch to 
take the place of tho ambroid comont boforo placing tho switch in the clip. 
Chock the adjustment as outlined above. 

Correct Temperature Sotting of Thormostats 

The correct cut-out temperature is 120° F, for the ENIAC units. 
Tho ventilating system was designed to permit approximately 11 rise ovor 
ambient temperature with now air filters. This would permit satisfactory 
oporation on days during which tho ambient temperature was 100° F allowing 

a safety margin, 

Tho equipment in tho power supply and bleeder cabinets vrill not 
be ondejigorod if tho temperature rises 20° F. and so the thermostats may 
bo sot up to 130° F if found noco.ssary. 

The absolute maximum temperature to which any of the ventilated 
equipment can bo safely subjected is 180° F. including tho thermostat bulb 
;ind duo consideration being given to tho possibility of "hot-spots" it is 
felt that the aforementioned settings are reasonable. 



XII _ 1 



' " ■ ■ 

12.1 List of Test Equipment 


Item 


Drawing 


Quantity 


.Remarks 


Bench 


PX^2-120 
2-121 
2-111 
2-112 
2-113 
2-114 


1 


2-111 signal wiring, 2-112 
power wiring, 113 switch 
panel, 114 fuse and by-pass- 
ing, 120 transformer, 121 
tube panel. 


P07vrer Supplies 


PX.2-102 
2-103 
2-104 


1 


6 supplies PX-2-102 
2 supplies PX-2-103 
1 bleeder PX;.2-104 


Synchronizing Unit 


PX- 2-115 
2-108 


1 


Front Panel PX-2-115 
Wiring Diagram PX-2-108 


Synchronizing Unit Supply 


PX- 2-107 


1 




Test Oscilloscope . 


PX-2-110 


1 


Includes probe with 4 detach- 
able ends. Connects to Syn- 
chronizing unit by cable. 


Test Oscillator 


FX-?^117 


1 


Connects to synchronizing 
unit by 1 conductor cable. 


Variable Power Supply 


PX-2-118 


1 


Connects to bench by four 
conductor cable. 


HiPot Supply 


r ' ""' 

FX-2-119 


1 




Tube Tester 


PX^ 2-116 


1 
1 


Voltohmist Jr. 




1 




Simpson Meter 




1 




12 Conductor Shielded Cable 
i 




2 


Connects only into sockets 
marked "S". 


12 Conductor Non-Shielded 
Cable 


t 


5 


3 connect synchronizing unit 
to its supply. 

1 connects variable supply 
to bench. 


4 Conductor Connection 
Cable 




2 

i , , 


2 Conductor Connection 
Gable 




1 


Connects synchronizing 
supply to AC 


12 to 10 Conductor Special 
Cable 




1 


To connect pulse araplifier 
to bench 


Load Box with 220 >•* 
resistors 


PX-4-163 


1 


For output load on pulse 
amplifier. 



b 



XII 



- 

12.1 List of Test Equipment (cont'd) 


Item 


Drawing | Quantity 


Remarks 


Tube Circuit Plug- in 
Tester 




2 




Plug-in Unit Pullers 




2 


For use in removing units 
from SNIAC. 


Current Flow Test Set 


- 


1 


Used to adjust relay- 
consists of tool box and 
contents. 


Static Tester 


FX- 2-109 


1 


For use with static test 
charts for SNIAC panel. 


Book of Photostats of 
Tliring and Test Drawings 




1 


Plug- in unit drawings. 


1 

1 Service Logs 




3 


1 for EIJIAC, 2 for units. 


+ ■ — ■ — — — — 

Push Switch and Cord 




1 


For maiiual pulse devices. 


Screwdriver 




1 




Diagonal Gutters 




1 




Long Nose Pliers 




1 




Soldering Iron 




1 




Variable Power Supply 
jidaptor 




1 


For connect fiig variable 
power supply to Multiplier, 
Cycling Unit:, and Function 
Table panelst. 



12,2 Description and i :aintenance 

The following chart (Table 12.2) lists the uses of the outputs 
of the synchronizing unit illustrated in drawing P:v-2-302 as used in 
testing the plug-in units as illustrated in drawing PX-2-301. 



Table 12.2 ■ 


Plug-in Unit 


Drawing 


Fixed 


Scope 


Variable 


Train 1 


'.'lir ing 


Test 


+ 


- 


PM and Clear Unit 


PX-5-108 


PX-5-127 






Clear Tubes 


Trans. Tubes 


PM Counter 


Acc. Decade Unit 


5-133 


5-126 
~ 5-129 






Carry Out 


Trans. Tubes 


Ring 


Ace. Transmitter Unit 


5-147 


Sets F.F. 




Resets F.F. , 
transmitter 






Acc. Receiver Unit 


5-148 


5-128 


Sets F.F. 




Resets F.F. 






Acc. Repeator Unit 


5-149 


5-130 






Ring (if 
trans, used) 




Ring (if no 
trans, used) 


Mult. Buff or Unit 


6-107 


6-130 






Drives buffo is 






! M.P. Decade Unit 
1 


8-101 


8-125 








+ and - trein operate MFPF 
unit 


! K.P. Program Unit j 8-103 


3-123 1 Sots F.F. 




Resets F.F. 


Drives stoppei 
gate 




li.P. Pulse Former 
and Carry Over 


8-104 


8-124 






"■'■■■ 1 


Drives PF 
through inv- 
erter 


Drives PP 
direct 


j Li. P. Transaittor Plug- 
in Unit 


" '8-105 ^ 


8-12S 






1 — .-. , _. , .. ■ ■■- -- 


Drives trans, 
gate 




M.P. Stopper Plug-in 
Unit 


8-112 


8-126 










Drives ring 


C.U. Transmitter Plug- 
in Unit 


9-102A 
9_102B 


9-123 










Drives 
inverters 


Reader Interlock Unit 9-103 


9-124 


Push button 
sets unsyn. 
F.F. 




Sets syn.f.f. 




Resets syn. 
f.f. 









Table 12.2 (cont'd) 


■ 


Plug- in Unit 


Draw 


in^ 


Fixed 


Scope 


Variable 


Train 


Wiring 


Test 


+ 


1 

1 


Reader Printer Start- 
ing Unit 


PX-9-104 


PX-9-a22 


Push Button 
resets 
reader f..f. 




Set reader 
and printer 
f.f. 


~* 


: _, 

Resets 
printer f.f. 


Initiating Pulse Plug- 
in Unit 


9-105 


9-125 


Push Button 
sets unsyn. 
f.f. 




Sets syn. f.f. 
Resets both 
f.f. and 
trems. pulse 






Reader Transmitter 
Plu&-in Unit 


9-106 


9-121 






Sets and 
resets f.f. 




1 


Cycling Unit Delay 
Line and Off Beat 
P.S. Unit 


9-130 
9-131 


1 

9-139 


■ 








Drives 
Palse Stan- 
dardizer 


Cycling Unit Oscilla- 
tor , Manual Pulsar 
Unit 


9-140 


Push Butt or 
operates 
Pulse 
former 


■ 








Cycling Unit On-beat 
Pulse Standardizor 
and Amp-Plug- in unit 


9-132 


9-141 










Drives 

Pulse Stan- 
dardizer 
and Amp. 


Constant Transmitter 
Pulse Boostor Unit 


11-115 


11-125 


- 
{ Drivos 

■ Buffer 






Pulse AiTiplifior 


4-116 


4-118 

■ '■ "— 








Drives Input 
Buffers 





XII - 5 

12,2.1 Maintenance of Test Equipmont 

Static and dynarriic test charts arc- provided for tho synchronizing 
unit and the tost oscilloccopo. Their nunbcrs are PX-2-112 and PX~3-110 
rcspootively. The variable povrar supply, the test oscillator, and the 
regulated power supplies are essentially of standard design so that 
maintenance can easily bo provided by direct use of the wiring drawings 
given in tho list in section 12.1. The tost bonch is essontially a wiring 
distribution socket panel similar in most rospoots to tho socket panels of 
the ENIAC proper. Thi fusing and AC power control features are copies of 

similar equipment for tho EIJIAC, Familiarity with ENIAC maintenance in 

which 
those respects provide ample background.togethcr with the v/iring diagrams 

appropriate to the test equipment are all that is necessary for tost 

equipment maintonanco. However, a word should bo added conoarning the 

special tube chassis in the test bench. This chassis contains a few 

tubes from tho accumulator gate clmssis, PX-5-117, essential to tho 

coupling of transceiver and repeater plug-in units when jointly operated as 

desired in testing from tiiue to tiino (sec illustration in block diagram 

PX-2-301). The circuits arc direct copies of the similarly named tubes on 

dravdng Pi-5-117 and no difficulty in maintaining them will be encountorod 

if this reference is kept in mind. The static panel tester is essentially 

a v/iring distribution panel and no particular problems should be encountered 

in maintaining it. Its use is described in section 12.3 below. The tube 

tester contains no special equipment and can best be maintained with 

reference to its v/iring drawing. A v/ord of caution on the tube tester, 

hov;ever, is that v/hen some of its fuses blow, erratic and unusual operation 

may occur so that before concluding some important failure has occurred, 



XII - 6 

the fuses should be checked. The operation of the tube tester is described 
in the detailed instructions engraved on its panel. 

12.3 Use of Tost Charts 

There is provided a static and dynairdc test chart for each 
plug-in unit as listed in section 12.1 and on drav/ing PX-S-133, a copy of 
v/hioh is inside tho left panel door of the test table. Also listed on 
PX-2-123 arc the names and wirinjj drar/ing numbers of the individual plug- 
in units. The description on the static-dynamic test drav/ing for each 
unit describes in detail the instructions necessary for carrying on the 
test program in accordance v;ith the chart in section 12.2. 

For the ENIAC "gate* panels, those scctionc vvhich are not 
removable plug-in units, there is provided static and dynamic tost charts 
just as thero are for the plug-in units themselves. A list of these 
charts is given in a table at the beginning of oach chapter for the units 
of the ENIAC under the column "Tost Charts". A special static tester, 
PX-2-109, v/as designed for use with those charts. By reference to 
drawing PX-5-109 and the "legend" and note above the panel illustration 
on each static tost chart, full information is found for the use of the 
static tester. 

12.4 Use of Tost Egui-pmont with EMIAC Proper 

The variable test oscillator, the variable power sv\pply, and the 
tost oscilloscope provide convonionces in testing the ENIaC, 
12.4.1 Test Oscillator 

In the cycling unit panel of tho ENIAC thoro is a socket and 
Bwltoh provided so that the test oscillator nay roplacc tho crystal 
controlled oscillator normally used in tho EIJIAC. By connecting the tost 



XII - 7 

oscillator, tho EKIAC may be oporatod at fastor or slower speeds providing 
means of checKing the frequency tolerance in built-in rings, and perhaps in 
localizing certain types of faulty operation. 

12.4.2 The Variable PoAver Supply 

By tho same token, the variable powor supply may be connected 
into function tablo, multiplier, and cycling unit by the uso of variable 
powor supply adaptor, P3U4-120, to provide voltage tolorancs tests on 
built-in rings in the ENIi'i.C. 

12.4.3 Tost Oscilloscopo 

Tho test oscilloscope is especially adaptable for synchronization 
from the central program pulses (CPP) of tho EiJlAC, and a special blank- 
ing circuit also provides for turning "on" or "off" any section of the 
s\7oep by control of tho central program pulses. 
12. 5 P lug-in Unit Tost Voltagos 

In most instances the plug-in units are tested with tho voltagos 
givon on tho wiring diagrams. Howovor, in some cases it vms expedient to 
tost at difforont voltagos. Tho tablo below gives those changes. 



XII - 8 



Plug- in Unit 


Wiring Diagram 
Voltages • 


Tost Table 
Voltages 


Master Programrnor Program 
(PX^8-103) 


+290 
+220 
+365 
+460 
+300 


-180 
-250 
-105 
- 10 
-170 


Master Progranffaor Transmittor 
(PX-8-105) 


+ 95 

+150 
+ 230 


+ 20 
+ 75 

+150 


Master Gyclor Reader Printer 
Startor (PX-9_104) 


+ 200 


+150 


Master Cyclor 
(PX-9_102) 


-345 
-475 
-120 
-295 




-130 

+225 
+ 50 


Constant Transmitter Pulso 
Booster (PX-11-115) 


+ 110 


+105 



MOORE SCHOOL OF ELECTRICAL ENGINEERING 
UNIVERSITY OF PENNSYLVANIA 



' • . 

INPUT X hJSG.^r,'V£ 

I 





5ccp£ 

i 



I 



■ 









r 




3 


'E 










O 


Z _ ._ 










7 


1 
















t> 


-■T 






' 




S 


4 






3 




4 







3 


v. 










H- 


V 




-f 




A 





J 






DRAWN BY _,._,. >;■. 5- i'-^(^ 



CHECKED BY //^ r 



APPROVED BY 



^ 



/ 5'.'?,V5-C£/,'/5,f- r.'--i>5;r£;f J EST LXAJ'lpLL 



SCALE 



\ 






O.SCILL.ATOf{ 

Input 



~n--o^--cMi>- 



6 



{~-j:zyti:±. 



-+ i__ 



T 



Zl 



<b ^^ h ^ V) h b %; t 

i ! i 1 I 1 1 ,1 .1 A 



6 



Ail I 41 J u ?! s^.s\ o-r 




i-^yTHfi/N (~) 



MOORE SCHOOL OF ELECTRICAL ENGINEERING 
UNIVERSITY OF PENNSYLVANIA 



r.l. 6YNc/if^oN/ziNG Unit diOCK DmGR/)n 



SCALE 



DRAWN BY 



CHECKED BY 



iTnik^ 



APPROVED BY 



PX-2-302 



f' 



i